I created a custom TextView that is displayed in a GridView. When the user taps on the TextView, a black circle has to be displayed in the center of this TextView. Actually this used to work fine on my tablet (an ASUS TF300, something like that). FYI all clicked textviews are then saved in a local database and can be loaded again.
I also tested that on a smartphone. Weird thing : the black circle is not displayed after a tap. However I know that it works because the black circles are well displayed if I save my UI and reload it again.
Did I miss something ?
Please find the code of the custom TextView below.
public class ChordItemTextView extends TextView {
// Properties
private ChordItem item;
public void setChordItem(ChordItem item)
{
this.item = item;
}
private Paint fretPaint;
private Paint chordPaint;
private Paint textPaint;
private int paperColor;
public ChordItemTextView(Context context) {
super(context);
this.Init(context);
}
public ChordItemTextView(Context context, AttributeSet attrs)
{
super(context, attrs);
this.Init(context);
}
private void Init(Context context)
{
// Resources retrieval
Resources myResources = getResources();
this.fretPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
this.fretPaint.setColor(myResources.getColor(R.color.fretColor));
this.chordPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
this.chordPaint.setColor(myResources.getColor(R.color.fretColor));
this.textPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
this.textPaint.setColor(myResources.getColor(R.color.fretIndication));
this.textPaint.setTextSize(myResources.getDimension(R.dimen.fretFontSize));
this.paperColor = myResources.getColor(R.color.bgColor);
}
#Override
protected void onDraw(Canvas canvas) {
// paper color
canvas.drawColor(this.paperColor);
// fret line drawing
canvas.drawLine(0, getMeasuredHeight() / 2, getMeasuredWidth(), getMeasuredHeight() / 2, this.fretPaint);
canvas.drawLine((float) (getMeasuredWidth() * 0.99), 0, (float) (getMeasuredWidth() * 0.99), getMeasuredHeight(), this.fretPaint);
if (this.item.getFretNumber() == 0)
{
canvas.drawLine((float)( getMeasuredWidth() * 0.95), 0, (float)( getMeasuredWidth() * 0.95), getMeasuredHeight(), this.fretPaint);
}
// "tap" drawing
if (this.item.getIsPushed())
{
canvas.drawCircle(getMeasuredWidth() / 2, getMeasuredHeight() / 2, getMeasuredHeight() / 4, this.chordPaint);
}
// fret number drawing
if (this.item.getStringNumber() == 1)
{
canvas.drawText(String.valueOf(this.item.getFretNumber()), getMeasuredWidth() / 2, getMeasuredHeight(), this.textPaint);
}
super.onDraw(canvas);
}
}
I have the following code that blows the app. Methods like drawLine work fine if they are directly inside "onDraw" but not if placed outside in a separate method as shown below. Does anyone have any idea what's wrong? The version with the method compiles ok but the app crashes when started.
Many thanks
Roberto
public class Painter extends View {
private static Canvas canvas;
private static Paint paintG = null;
public static int screenW; // screen width
public static int screenH; // screen height
private String tag = "Painter";
public Painter(Context context) {
super(context);
readDrawingData();
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
screenW = canvas.getWidth(); // screen width
screenH = canvas.getHeight(); // screen height
Rect allScreen = new Rect(0, 0, screenW, screenH);
// works OK
paintG = new Paint();
paintG.setAntiAlias(true);
paintG.setStrokeWidth(2);
paintG.setStyle(Paint.Style.FILL);
paintG.setColor(0xFFf7f9d2);
canvas.drawRect(allScreen, paintG);
// paint circle/oval - works OK
double R = ((screenW > screenH) ? screenH : screenW) / 2 - 100;
double Z = R + 20;
double X = screenW /2;
double Y = screenH /2;
RectF oval1 = new RectF(Math.round(X-R), Math.round(Y-R),
Math.round(X+R), Math.round(Y+R));
paintG.setStyle(Paint.Style.STROKE);
paintG.setColor(0xffff0000);
canvas.drawOval(oval1, paintG);
// this code works OK here
paintG.setColor(0xffff0000);
if (i > 0) {
for (int j=0; j<i; j++) {
canvas.drawLine(x1[j], y1[j], x2[j], y2[j], paintG);
}
}
// calling this will crash app
paintDrawing();
}
// ************************************************************
void paintDrawing() {
// PROBLEM: same code as above - causes app to crash...
// when outside onDraw
paintG.setColor(0xffff0000);
if (i > 0) {
for (int j=0; j<i; j++) {
canvas.drawLine(x1[j], y1[j], x2[j], y2[j], paintG);
}
}
// ************************************************************
}
I have created an app that actually uses flood fill algorithm to fill colors in bitmaps. I have created some bitmaps (200x200) but I don't know the exact size of bitmap that I should create, I want bitmaps to cover full screen and when I scale bitmaps, they become blur and flood fill doesn't work on them. I saw an app that used GridView to show images and click on image started new activity with image covering full screen. How can I achieve this. Attached is CustomImage that I've use to show bitmap. Any help will be appreciated.
EDITED: I know that GridView doesn't scale up image to full screen, it use another image. That app behaves same for different screen size, those image fill screen of any size without effecting the quality.
public class CustomImage extends View {
public CustomImage(Context context) {
super(context);
} // end constructor
public CustomImage(Context context, int resource_id) {
super(context);
mPaint = new Paint();
mPaint.setColor(Color.WHITE);
mPoint = new Point();
mProgressIndicator = (ProgressIndicator) context;
mBitmap = BitmapFactory.decodeResource(getResources(), resource_id)
.copy(Bitmap.Config.ARGB_8888, true);
} // end constructor
#Override
protected void onDraw(Canvas canvas) {
// draw image
canvas.drawBitmap(mBitmap, 0, 0, mPaint);
} // end onDraw
#Override
public boolean onTouchEvent(MotionEvent event) {
int bWidth = mBitmap.getWidth();
int bHeight = mBitmap.getHeight();
mPoint.x = (int) event.getX();
mPoint.y = (int) event.getY();
mPoint.x = (mPoint.x > bWidth) ? (bWidth - 5) : mPoint.x;
mPoint.y = (mPoint.y > bHeight) ? (bHeight - 5) : mPoint.y;
switch (event.getAction()) {
// called when screen clicked i.e New touch started
case MotionEvent.ACTION_DOWN:
mProgressIndicator.updateProgress(0);
new Filler(mBitmap, mPoint, mPaint.getColor(), mBitmap.getPixel(
mPoint.x, mPoint.y), this).execute();
invalidate();
} // end Case
return true;
} // end onTouchEvent
public void setColor(int color) {
mPaint.setColor(color);
} // end setColor
} // end Class
The GridView you have seen might be using two versions of the same image. One as a big image and another as a scaled down thumbnail image for the grid.
I'm working on an audio vu meter and I'd like to get something like the image shown below, with audio amplitude shown in real-time.
I know how to get the audio amplitude for each channel, but I'm not sure how to do a fast enough display of the colored rectangles.
My first idea is to of have a View with a background color for each rectangle and showing/hiding it according to the amplitude.
Has anybody already tried that? Would it be fast enough for displaying the amplitude every 50 or 100ms?
What's the fastest way of achieving that?
Thanks you
So you want to make as many views as you have rectangle and change their visibility?
Don't do that. It will be a mess inside your layout. Instead make a custom view and override onDraw(). Inside onDraw you use canvas.drawRect() to draw the rectangles. You will get easily 30-60 frames per second this way.
This is a simple and uncomplete example but should get you on the right track.
private class AmplitudeView extends View {
private int mWidth;
private int mHeight;
private Paint mRectPaint;
public AmplitudeView(Context context, AttributeSet attrs) {
super(context, attrs);
mRectPaint = new Paint() {
{
setStyle(Style.FILL);
}
};
}
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mWidth = w;
mHeight = h;
}
#Override
protected void onDraw(Canvas canvas) {
int numRects = 10;
int red = 255;
int green = 0;
int incr = 255/numRects;
for (int i = 0; i< numRects;i++){
//TODO calculate color based on amplitude
mRectPaint.setColor(Color.argb(0xff, red, green, 0));
//TODO calculate rectangle
canvas.drawRect(r, mRectPaint);
red-=incr;
green+=incr;
}
}
}
[UPDATE]
To conclude this question, I implemented my graph using the following two methods (see below). drawCurve() receives a Canvas and an array of float. The array is properly filled (timestamps are assumed by the value index in the array) and varies from 0.0 to 1.0. The array is sent to prepareWindowArray() that takes a chunk of the array from position windowStart for windowSize-values, in a circular manner.
The array used by the GraphView and by the data provider (a Bluetooth device) is the same. A Class in the middle ensures that GraphView is not reading data that are being written by the Bluetooth device. Since the GraphView always loop thru the array and redraw it at every iteration, it will update according to the data written by the Bluetooth device, and by forcing the write frequency of the Bluetooth device to the refresh frequency of the Graph, I obtain a smooth animation of my signal.
The GraphView's invalidate() method is called by the Activity, which run a Timer to refresh the graph at every x milliseconds. The frequency at which the graph is refreshed is dynamically set, so that it adapt to the flow of data from the Bluetooth device (which specify the frequency of its signal in the header of its packet).
Find the complete code of my GraphView in the answer I wrote below (in the answer section). If you guys find errors or way to optimize it, please let me know; it would be greatly appreciated!
/**
* Read a buffer array of size greater than "windowSize" and create a window array out of it.
* A curve is then drawn from this array using "windowSize" points, from left
* to right.
* #param canvas is a Canvas object on which the curve will be drawn. Ensure the canvas is the
* later drawn object at its position or you will not see your curve.
* #param data is a float array of length > windowSize. The floats must range between 0.0 and 1.0.
* A value of 0.0 will be drawn at the bottom of the graph, while a value of 1.0 will be drawn at
* the top of the graph. The range is not tested, so you must ensure to pass proper values, or your
* graph will look terrible.
* 0.0 : draw at the bottom of the graph
* 0.5 : draw in the middle of the graph
* 1.0 : draw at the top of the graph
*/
private void drawCurve(Canvas canvas, float[] data){
// Create a reference value to determine the stepping between each points to be drawn
float incrementX = (mRightSide-mLeftSide)/(float) windowSize;
float incrementY = (mBottomSide - mTopSide);
// Prepare the array for the graph
float[] source = prepareWindowArray(data);
// Prepare the curve Path
curve = new Path();
// Move at the first point.
curve.moveTo(mLeftSide, source[0]*incrementY);
// Draw the remaining points of the curve
for(int i = 1; i < windowSize; i++){
curve.lineTo(mLeftSide + (i*incrementX), source[i] * incrementY);
}
canvas.drawPath(curve, curvePaint);
}
The prepareWindowArray() method that implement the circular behavior of the array:
/**
* Extract a window array from the data array, and reposition the windowStart
* index for next iteration
* #param data the array of data from which we get the window
* #return an array of float that represent the window
*/
private float[] prepareWindowArray(float[] data){
// Prepare the source array for the graph.
float[] source = new float[windowSize];
// Copy the window from the data array into the source array
for(int i = 0; i < windowSize; i++){
if(windowStart+i < data.length) // If the windows holds within the data array
source[i] = data[windowStart + i]; // Simply copy the value in the source array
else{ // If the window goes beyond the data array
source[i] = data[(windowStart + 1)%data.length]; // Loop at the beginning of the data array and copy from there
}
}
// Reposition the buffer index
windowStart = windowStart + windowSize;
// If the index is beyond the end of the array
if(windowStart >= data.length){
windowStart = windowStart % data.length;
}
return source;
}
[/UPDATE]
I'm making an app that read data from a Bluetooth device at a fixed rate. Everytime that I have new data, I want them to be plotted on the graph to the right, and to translate the remainder of the graph to the left in realtime. Basically, like an oscilloscope would do.
So I made a custom View, with xy axis, a title and units. To do this, I simply draw those things on the View canvas. Now I want to draw the curve. I manage to draw a static curve from an already filled array using this method:
public void drawCurve(Canvas canvas){
int left = getPaddingLeft();
int bottom = getHeight()-getPaddingTop();
int middle = (bottom-10)/2 - 10;
curvePaint = new Paint();
curvePaint.setColor(Color.GREEN);
curvePaint.setStrokeWidth(1f);
curvePaint.setDither(true);
curvePaint.setStyle(Paint.Style.STROKE);
curvePaint.setStrokeJoin(Paint.Join.ROUND);
curvePaint.setStrokeCap(Paint.Cap.ROUND);
curvePaint.setPathEffect(new CornerPathEffect(10) );
curvePaint.setAntiAlias(true);
mCurve = new Path();
mCurve.moveTo(left, middle);
for(int i = 0; i < mData[0].length; i++)
mCurve.lineTo(left + ((float)mData[0][i] * 5), middle-((float)mData[1][i] * 20));
canvas.drawPath(mCurve, curvePaint);
}
It gives me something like this.
There are still things to fix on my graph (the sub-axis are not properly scaling), but these are details I can fix later.
Now I want to change this static graph (that receives a non-dynamic matrice of values) with something dynamic that would redraw the curve every 40ms, pushing the old data to the left and plotting the new data to the right, so I could visualise in real time the information provided by the Bluetooth device.
I know there are some graphing package that exists already, but I'm kinda noob with these things and I'd like to pratice by implementing this graph myself. Also, most of my GraphView class is done, except for the curve part.
Second question, I'm wondering how I should send the new values to the graph. Should I use something like a FIFO stack, or can I achieve what I want with a simple matrice of doubles?
On a side note, the 4 fields at the bottom are already dynamically updated. Well, they are kind of faking the "dynamic", they loop thru the same double matrice again and again, they don't actually take fresh values.
Thanks for your time! If something's unclear about my question, let me know and I'll update it with more details.
As mentioned in my question, here's the class that I designed to solve my problems.
/**
* A View implementation that displays a scatter graph with
* automatic unit scaling.
*
* Call the <i>setupGraph()</i> method to modify the graph's
* properties.
* #author Antoine Grondin
*
*/
public class GraphView extends View {
//////////////////////////////////////////////////////////////////
// Configuration
//////////////////////////////////////////////////////////////////
// Set to true to impose the graph properties
private static final boolean TEST = false;
// Scale configuration
private float minX = 0; // When TEST is true, these values are used to
private float maxX = 50; // Draw the graph
private float minY = 0;
private float maxY = 100;
private String titleText = "A Graph...";
private String xUnitText = "s";
private String yUnitText = "Volts";
// Debugging variables
private boolean D = true;
private String TAG = "GraphView";
//////////////////////////////////////////////////////////////////
// Member fields
//////////////////////////////////////////////////////////////////
// Represent the borders of the View
private int mTopSide = 0;
private int mLeftSide = 0;
private int mRightSide = 0;
private int mBottomSide = 0;
private int mMiddleX = 0;
// Size of a DensityIndependentPixel
private float mDips = 0;
// Hold the position of the axis in regard to the range of values
private int positionOfX = 0;
private int positionOfY = 0;
// Index for the graph array window, and size of the window
private int windowStart = 0;
private int windowSize = 128;
private float[] dataSource;
// Painting tools
private Paint xAxisPaint;
private Paint yAxisPaint;
private Paint tickPaint;
private Paint curvePaint;
private Paint backgroundPaint;
private TextPaint unitTextPaint;
private TextPaint titleTextPaint;
// Object to be drawn
private Path curve;
private Bitmap background;
///////////////////////////////////////////////////////////////////////////////
// Constructors
///////////////////////////////////////////////////////////////////////////////
public GraphView(Context context) {
super(context);
init();
}
public GraphView(Context context, AttributeSet attrs){
super(context, attrs);
init();
}
public GraphView(Context context, AttributeSet attrs, int defStyle){
super(context, attrs, defStyle);
init();
}
///////////////////////////////////////////////////////////////////////////////
// Configuration methods
///////////////////////////////////////////////////////////////////////////////
public void setupGraph(String title, String nameOfX, float min_X, float max_X, String nameOfY, float min_Y, float max_Y){
if(!TEST){
titleText = title;
xUnitText = nameOfX;
yUnitText = nameOfY;
minX = min_X;
maxX = max_X;
minY = min_Y;
maxY = max_Y;
}
}
/**
* Set the array this GraphView is to work with.
* #param data is a float array of length > windowSize. The floats must range between 0.0 and 1.0.
* A value of 0.0 will be drawn at the bottom of the graph, while a value of 1.0 will be drawn at
* the top of the graph. The range is not tested, so you must ensure to pass proper values, or your
* graph will look terrible.
* 0.0 : draw at the bottom of the graph
* 0.5 : draw in the middle of the graph
* 1.0 : draw at the top of the graph
*/
public void setDataSource(float[] data){
this.dataSource = data;
}
///////////////////////////////////////////////////////////////////////////////
// Initialization methods
///////////////////////////////////////////////////////////////////////////////
private void init(){
initDrawingTools();
}
private void initConstants(){
mDips = getResources().getDisplayMetrics().density;
mTopSide = (int) (getTop() + 10*mDips);
mLeftSide = (int) (getLeft() + 10*mDips);
mRightSide = (int) (getMeasuredWidth() - 10*mDips);
mBottomSide = (int) (getMeasuredHeight() - 10*mDips);
mMiddleX = (mRightSide - mLeftSide)/2 + mLeftSide;
}
private void initWindowSetting() throws IllegalArgumentException {
// Don't do anything if the given values make no sense
if(maxX < minX || maxY < minY ||
maxX == minX || maxY == minY){
throw new IllegalArgumentException("Max and min values make no sense");
}
// Transform the values in scanable items
float[][] maxAndMin = new float[][]{
{minX, maxX},
{minY, maxY}};
int[] positions = new int[]{positionOfY, positionOfX};
// Place the X and Y axis in regard to the given max and min
for(int i = 0; i<2; i++){
if(maxAndMin[i][0] < 0f){
if(maxAndMin[i][1] < 0f){
positions[i] = (int) maxAndMin[i][0];
} else{
positions[i] = 0;
}
} else if (maxAndMin[i][0] > 0f){
positions[i] = (int) maxAndMin[i][0];
} else {
positions[i] = 0;
}
}
// Put the values back in their right place
minX = maxAndMin[0][0];
maxX = maxAndMin[0][1];
minY = maxAndMin[1][0];
maxY = maxAndMin[1][1];
positionOfY = mLeftSide + (int) (((positions[0] - minX)/(maxX-minX))*(mRightSide - mLeftSide));
positionOfX = mBottomSide - (int) (((positions[1] - minY)/(maxY-minY))*(mBottomSide - mTopSide));
}
private void initDrawingTools(){
xAxisPaint = new Paint();
xAxisPaint.setColor(0xff888888);
xAxisPaint.setStrokeWidth(1f*mDips);
xAxisPaint.setAlpha(0xff);
xAxisPaint.setAntiAlias(true);
yAxisPaint = xAxisPaint;
tickPaint = xAxisPaint;
tickPaint.setColor(0xffaaaaaa);
curvePaint = new Paint();
curvePaint.setColor(0xff00ff00);
curvePaint.setStrokeWidth(1f*mDips);
curvePaint.setDither(true);
curvePaint.setStyle(Paint.Style.STROKE);
curvePaint.setStrokeJoin(Paint.Join.ROUND);
curvePaint.setStrokeCap(Paint.Cap.ROUND);
curvePaint.setPathEffect(new CornerPathEffect(10));
curvePaint.setAntiAlias(true);
backgroundPaint = new Paint();
backgroundPaint.setFilterBitmap(true);
titleTextPaint = new TextPaint();
titleTextPaint.setAntiAlias(true);
titleTextPaint.setColor(0xffffffff);
titleTextPaint.setTextAlign(Align.CENTER);
titleTextPaint.setTextSize(20f*mDips);
titleTextPaint.setTypeface(Typeface.MONOSPACE);
unitTextPaint = new TextPaint();
unitTextPaint.setAntiAlias(true);
unitTextPaint.setColor(0xff888888);
unitTextPaint.setTextAlign(Align.CENTER);
unitTextPaint.setTextSize(20f*mDips);
unitTextPaint.setTypeface(Typeface.MONOSPACE);
}
///////////////////////////////////////////////////////////////////////////////
// Overridden methods
///////////////////////////////////////////////////////////////////////////////
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
regenerateBackground();
}
public void onDraw(Canvas canvas){
drawBackground(canvas);
if(dataSource != null)
drawCurve(canvas, dataSource);
}
///////////////////////////////////////////////////////////////////////////////
// Drawing methods
///////////////////////////////////////////////////////////////////////////////
private void drawX(Canvas canvas){
canvas.drawLine(mLeftSide, positionOfX, mRightSide, positionOfX, xAxisPaint);
canvas.drawText(xUnitText, mRightSide - unitTextPaint.measureText(xUnitText)/2, positionOfX - unitTextPaint.getTextSize()/2, unitTextPaint);
}
private void drawY(Canvas canvas){
canvas.drawLine(positionOfY, mTopSide, positionOfY, mBottomSide, yAxisPaint);
canvas.drawText(yUnitText, positionOfY + unitTextPaint.measureText(yUnitText)/2 + 4*mDips, mTopSide + (int) (unitTextPaint.getTextSize()/2), unitTextPaint);
}
private void drawTick(Canvas canvas){
// No tick at this time
// TODO decide how I want to put those ticks, if I want them
}
private void drawTitle(Canvas canvas){
canvas.drawText(titleText, mMiddleX, mTopSide + (int) (titleTextPaint.getTextSize()/2), titleTextPaint);
}
/**
* Read a buffer array of size greater than "windowSize" and create a window array out of it.
* A curve is then drawn from this array using "windowSize" points, from left
* to right.
* #param canvas is a Canvas object on which the curve will be drawn. Ensure the canvas is the
* later drawn object at its position or you will not see your curve.
* #param data is a float array of length > windowSize. The floats must range between 0.0 and 1.0.
* A value of 0.0 will be drawn at the bottom of the graph, while a value of 1.0 will be drawn at
* the top of the graph. The range is not tested, so you must ensure to pass proper values, or your
* graph will look terrible.
* 0.0 : draw at the bottom of the graph
* 0.5 : draw in the middle of the graph
* 1.0 : draw at the top of the graph
*/
private void drawCurve(Canvas canvas, float[] data){
// Create a reference value to determine the stepping between each points to be drawn
float incrementX = (mRightSide-mLeftSide)/(float) windowSize;
float incrementY = mBottomSide - mTopSide;
// Prepare the array for the graph
float[] source = prepareWindowArray(data);
// Prepare the curve Path
curve = new Path();
// Move at the first point.
curve.moveTo(mLeftSide, source[0]*incrementY);
// Draw the remaining points of the curve
for(int i = 1; i < windowSize; i++){
curve.lineTo(mLeftSide + (i*incrementX), source[i] * incrementY);
}
canvas.drawPath(curve, curvePaint);
}
///////////////////////////////////////////////////////////////////////////////
// Intimate methods
///////////////////////////////////////////////////////////////////////////////
/**
* When asked to draw the background, this method will verify if a bitmap of the
* background is available. If not, it will regenerate one. Then, it will draw
* the background using this bitmap. The use of a bitmap to draw the background
* is to avoid unnecessary processing for static parts of the view.
*/
private void drawBackground(Canvas canvas){
if(background == null){
regenerateBackground();
}
canvas.drawBitmap(background, 0, 0, backgroundPaint);
}
/**
* Call this method to force the <i>GraphView</i> to redraw the cache of it's background,
* using new properties if you changed them with <i>setupGraph()</i>.
*/
public void regenerateBackground(){
initConstants();
try{
initWindowSetting();
} catch (IllegalArgumentException e){
Log.e(TAG, "Could not initalize windows.", e);
return;
}
if(background != null){
background.recycle();
}
background = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
Canvas backgroundCanvas = new Canvas(background);
drawX(backgroundCanvas);
drawY(backgroundCanvas);
drawTick(backgroundCanvas);
drawTitle(backgroundCanvas);
}
/**
* Extract a window array from the data array, and reposition the windowStart
* index for next iteration
* #param data the array of data from which we get the window
* #return an array of float that represent the window
*/
private float[] prepareWindowArray(float[] data){
// Prepare the source array for the graph.
float[] source = new float[windowSize];
// Copy the window from the data array into the source array
for(int i = 0; i < windowSize; i++){
if(windowStart+i < data.length) // If the windows holds within the data array
source[i] = data[windowStart + i]; // Simply copy the value in the source array
else{ // If the window goes beyond the data array
source[i] = data[(windowStart + 1)%data.length]; // Loop at the beginning of the data array and copy from there
}
}
// Reposition the buffer index
windowStart = windowStart + windowSize;
// If the index is beyond the end of the array
if(windowStart >= data.length){
windowStart = windowStart % data.length;
}
return source;
}
}
Well I would start by just trying to redraw it all with the code you have and real dynalic data. Only if that is not quick enough do you need to try anything fancy like scrolling...
If you need fancy I would try somthing like this.
I would draw the dynamic part of the graph into a secondary Bitmap that you keep between frames rather than directly to the canves. I would have the background none dynamic part of the graph in another bitmap that only gets drawen on rescale etc.
In this secondary dynamic bitmap when ploting new data you first need to clear the old data you are replacing you do this by drawing the apropriate slice of the static background bitmap over the top of the stale data, thus clearing it and geting the background nice and fresh again. You then just need to draw your new bit of dynamic data. The trick is that You draw into this second bitmap left to right then just wrap back to the left at the end and start over.
To get from the soncodary bitmap to your cancas draw the bitmap to the canvas in two parts. The older data to the right of what you just added needs to be drawn onto the left part of your final canvas and the new data needs to be drawn imediatly to the right of it.
For sending the data a circular buffer would be the normal thing for this sort of data where once it's off the graph you don't care about it.