i have a bitmap inside a canvas.the class implements ontouchlistener.i need to hide the image while touch on the image.
class Panel extends View implements View.OnTouchListener {
Paint linepaint=new Paint();
public Panel(Context context) {
super(context);
}
#Override
public void onDraw(Canvas canvas) {
Bitmap imgtable = BitmapFactory.decodeResource(getResources(), R.drawable.table_01);
canvas.drawBitmap(imgtable, centrex, centrey, null);
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
return false;
}
}
Make on touch listener for the view where you draw the image. And there change the visibility of the view. Not in onDraw();
Edit:
If you set the Bitmap image for example on a ImageView, then onTouchListener() must be applied on the ImageView. Bitmap image is only a data that is supplied to the view(s).
Related
I am unable to get the canvas object in ontouch().Without the canvas I cannot draw a circle when touched.How can I draw any shape or image when touched
public class Board extends View implements View.OnTouchListener {
public Board(Context context) {
super(context);
Paint paint1 = new Paint();
paint1.setTextSize(50);
paint1.setColor(Color.WHITE);
View view=this;
view.setOnTouchListener(this);
}
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawRGB(200, 100, 0);
}
#Override
public boolean onTouch(View v, MotionEvent event) {
final int action = MotionEventCompat.getActionMasked(event);
int pointer = MotionEventCompat.getActionIndex(event);
if (action == MotionEvent.ACTION_DOWN) {
canvas.drawCircle(70, 1100, 50, paint1);
}
return false;
}
To draw on canvas wherever you touch, you need a path to keep track of your touch points and path. Using the path object you can draw on canvas. See this answer Draw on touch
I am trying to implement a Drawing Application in Android. Where the user should be able to select and move the drawn shapes.
Currently i have statically drawn some rects and text on my Drawing Canvas:
View mDrawingCanvas = new View(mContext)
{
ShapeDrawable rectangle;
#Override
public boolean isFocused() {
// TODO Auto-generated method stub
Log.d(TAG, "View's On focused is called !");
return super.isFocused();
}
#Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
return super.onTouchEvent(event);
}
#Override
protected void onDraw(final Canvas canvas) {
super.onDraw(canvas);
// Work out current total scale factor
// from source to view
final float scale = mSourceScale*(float)getWidth()/(float)mSize.x;
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.WHITE);
//Custom View
rectangle = new ShapeDrawable(new RectShape());
rectangle.getPaint().setColor(Color.GRAY);
rectangle.getPaint().setStyle(Paint.Style.FILL_AND_STROKE);
rectangle.getPaint().setStrokeWidth(3);
rectangle.setBounds((int)(50*scale), (int)(30*scale), (int)(200*scale), (int)(150*scale));
rectangle.draw(canvas);
rectangle.getPaint().setColor(Color.BLUE);
rectangle.getPaint().setStyle(Paint.Style.FILL_AND_STROKE);
rectangle.getPaint().setStrokeWidth(3);
rectangle.setBounds((int)(200*scale), (int)(200*scale), (int)(400*scale), (int)(350*scale));
rectangle.draw(canvas);
}
};
I want to select (draw borders on the selected shape) and move the drawn Shapes in onTouch events of the drawing canvas.
Can some one please guide me about this, any help is Highly Appreciated.
This answer has demonstrated the Shape Moving Methodology that i was looking for.
And my problem is solved now. The Link is :
Drag and move a circle drawn on canvas
You should save the X and Y positions in the touch event and use them when drawing your shapes.
Below is a very basic example of how to do this, but you need to improve it (check if the touch is inside the object and only change values for that object)
Example:
public class DrawTest extends View {
private static final String TAG = "Desenho";
private ShapeDrawable rectangle;
private Paint paint;
private float currX, currY;
private Rect blue, gray;
public DrawTest(Context context) {
super(context);
currX = 1;
currY = 1;
gray = new Rect(50,30,200,150);
blue = new Rect(200,200,400,350);
paint = new Paint();
rectangle = new ShapeDrawable(new RectShape());
}
#Override
public boolean isFocused() {
Log.d(TAG, "View's On focused is called !");
return super.isFocused();
}
#Override
public boolean onTouchEvent(MotionEvent event) {
currX = event.getX();
currY = event.getY();
invalidate();
Log.d(TAG, "View's On touch is called! X= "+currX + ", Y= "+currY);
return super.onTouchEvent(event);
}
#Override
protected void onDraw(final Canvas canvas) {
super.onDraw(canvas);
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.WHITE);
//Custom View
rectangle.getPaint().setColor(Color.GRAY);
rectangle.getPaint().setStyle(Paint.Style.FILL_AND_STROKE);
rectangle.getPaint().setStrokeWidth(3);
gray.set((int)(50+currX), (int)(30+currY), (int)(200+currX), (int)(150+currY));
rectangle.setBounds(gray);
gray = rectangle.getBounds();
rectangle.draw(canvas);
rectangle.getPaint().setColor(Color.BLUE);
rectangle.getPaint().setStyle(Paint.Style.FILL_AND_STROKE);
rectangle.getPaint().setStrokeWidth(3);
blue.set((int)(200+currX), (int)(200+currY), (int)(400+currX), (int)(350+currY));
rectangle.setBounds(blue);
blue = rectangle.getBounds();
rectangle.draw(canvas);
}
}
I am having doubt related to working of canvas while drawing , it is mentioned that canvas holds the drawing calls and bitmap holds the actual pixel data ,for e.g in the code
public class MyView extends View{
private Paint _p;
public float x=10,y=10;
private Canvas _canvas;
static int cnt=0;
public MyView(Context context) {
super(context);
// TODO Auto-generated constructor stub
_p = new Paint();
_p.setColor(Color.GREEN);
_canvas = new Canvas();
this.setOnTouchListener(new OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
cnt++;
_canvas.drawCircle(event.getX(), event.getY(), 10, _p);
if(cnt>3){
cnt = 0;
invalidate();
}
return false;
}
});
}
public void onDraw(Canvas can){
_canvas = can;
super.onDraw(_canvas);
_canvas.drawColor(Color.BLACK);
_canvas.drawCircle(x, y, 10, _p);
x = x +10;
y= y+10;
}
}
3 circles should be drawn but it is not the case , can anybody please explain me?thanks in advance
Regards,
Rohit
Your onTouch only has a one time check to draw the circle, it's not a recursive loop to keep drawing until 3 are drawn. This is assuming your _canvase.drawCircle() event (which isn't shown) doesn't draw 3 circles.
Im developing an application which having Images as a Index on selection of particular image that activity will begin but I dont know how to set onClickListener or onTouchListener in Canvas heres my code
public class DrawView extends View implements OnTouchListener {
LinearLayout mLayout;
Bitmap index;
Bitmap book;
Bitmap bird;
Bitmap game;
Bitmap mail;
Bitmap music;
Bitmap torch;
Paint paint;
public DrawView(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
this.setOnTouchListener(this);
index = BitmapFactory.decodeResource(getResources(), R.drawable.photo1);
book = BitmapFactory.decodeResource(getResources(), R.drawable.book);
game = BitmapFactory.decodeResource(getResources(), R.drawable.game);
music = BitmapFactory.decodeResource(getResources(), R.drawable.music);
}
public void onDraw(Canvas canvas){
paint = new Paint();
Bitmap indexcanvas = Bitmap.createScaledBitmap(index, canvas.getWidth(),
canvas.getHeight(), true);
canvas.drawBitmap(indexcanvas, 0, 0, paint);
canvas.drawBitmap(book, 160, 100, paint);
canvas.drawBitmap(game, 30, 10, paint);
canvas.drawBitmap(music, 80, 50, paint);
}
public boolean onTouch(View v, MotionEvent event) {
return false;
}
Please if anyone knows how to add onClickListener for particular image e.g. here if I click on Book then bookActivity will start.
try something like this:
public boolean onTouch(View v, MotionEvent event) {
if((event.getX(0)>=160) &&
(event.getY(0)>=100) &&
( event.getX(0)<=160+BOOK_IMG_WIDTH) &&
(event.getY(0)<=100+BOOK_IMG_HEIGHT))
{
//book selected
}
return true;
}
Use ImageView instead of bitmap and add it to your layout:
book = new ImageView(context);
book.setImageResource(R.drawable.book);
book.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
/*...*/
}
};);
Save the images' coords in an ArrayList. Set OnClickListener on the context, get the point coords that has been clicked, find the image in the arraylist and do something :)
I'd Like to know how to draw a Line on ImageView as user swipe their finger ?
Could any body explain this ? Or perhaps any Link to get start on this.
You must have your own ImageView and override onDraw function. Use something like this
public class MyImageView extends ImageView{
public MyImageView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
canvas.drawLine(0, 0, 20, 20, p);
}
}
and in your main class create object MyImageView; and when you touch your display call the update(); function
This is a complete example of how you can draw green rectangle over another image:
package CustomWidgets;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
/**
* Allows to draw rectangle on ImageView.
*
* #author Maciej Nux Jaros
*/
public class DrawImageView extends ImageView {
private Paint currentPaint;
public boolean drawRect = false;
public float left;
public float top;
public float right;
public float bottom;
public DrawImageView(Context context, AttributeSet attrs) {
super(context, attrs);
currentPaint = new Paint();
currentPaint.setDither(true);
currentPaint.setColor(0xFF00CC00); // alpha.r.g.b
currentPaint.setStyle(Paint.Style.STROKE);
currentPaint.setStrokeJoin(Paint.Join.ROUND);
currentPaint.setStrokeCap(Paint.Cap.ROUND);
currentPaint.setStrokeWidth(2);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (drawRect)
{
canvas.drawRect(left, top, right, bottom, currentPaint);
}
}
}
When you have this defined you can replace ImageView with above View (widget) for example:
<CustomWidgets.DrawImageView
android:id="#+id/widgetMap"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:src="#drawable/map_small"
/>
Then you can use this for example in touch event of the activity that controls the layout:
mapImageView.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
DrawImageView drawView = (DrawImageView) v;
// set start coords
if (event.getAction() == MotionEvent.ACTION_DOWN) {
drawView.left = event.getX();
drawView.top = event.getY();
// set end coords
} else {
drawView.right = event.getX();
drawView.bottom = event.getY();
}
// draw
drawView.invalidate();
drawView.drawRect = true;
return true;
}
});
Of course you could make some getters and setters and other Java over-engineering routines ;-).
For drawing the line the user actually drew you have to override the dispatchTouchEvent. From that event you can get the coordinates of the line and draw them in the onDraw as shown by george.
http://developer.android.com/reference/android/app/Activity.html#dispatchTouchEvent(android.view.MotionEvent)
Take a look at the ApiDemos sample FingerPaint.
By using this you can draw line on ImageView by touching on the screen.