Develop Reference

How to use android canvas to draw a striped rectangle?

rectangles
I already drew the left rounded rectangle. I need to insert some lines horizontally for it to become a striped rectangle. How can I achieve this?
I already tried to use path and draw a line. But nothing worked how it was supposed to. Can someone help me?

Here's a sample code for drawing a striped rectangle in Android Canvas:
public class StripeRectView extends View {
private Paint mPaint;
private int mStripeWidth = 10;
private int mStripeHeight = 10;
public StripeRectView(Context context) {
super(context);
init();
}
public StripeRectView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public StripeRectView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
mPaint = new Paint();
mPaint.setColor(Color.BLACK);
mPaint.setStyle(Paint.Style.FILL);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int x = 0;
int y = 0;
while (y <= getHeight()) {
canvas.drawRect(x, y, x + mStripeWidth, y + mStripeHeight, mPaint);
x += mStripeWidth * 2;
if (x > getWidth()) {
x = 0;
y += mStripeHeight * 2;
}
}
}
}
the Canvas is used to draw rectangles, with alternating stripes of width mStripeWidth and height mStripeHeight until the entire height of the View is filled. You can modify it according to your needs.

Android: Custom circle ProgressBar with spaces in between

I am trying to create a custom view that has a Circle and in it, I have to have sections in run time as shown in the image below. I tried a lot of stuff in onDraw method but got no luck. I even tried https://github.com/donvigo/CustomProgressControls . Basically, I want to give a number of sections and then in each section I can select colors as per my need.
I am looking for ProgressBar that should have gap/space as shown in the image; in between circles. Say if I have given 5 sections, 3 of which should be "full", it should color the first 3 in red, and the other 2 in green, for example.
To draw I am doing like:
private void initExternalCirclePainter() {
internalCirclePaint = new Paint();
internalCirclePaint.setAntiAlias(true);
internalCirclePaint.setStrokeWidth(internalStrokeWidth);
internalCirclePaint.setColor(color);
internalCirclePaint.setStyle(Paint.Style.STROKE);
internalCirclePaint.setPathEffect(new DashPathEffect(new float[]{dashWith, dashSpace}, dashSpace));
}

I might be a little late to the party, but I actually wrote a custom component that has 2 rings that look quite similar to what you're trying to achieve. You can just remove the outer ring easily. The image of what I got in the end:
Here's the class:
public class RoundedSectionProgressBar extends View {
// The amount of degrees that we wanna reserve for the divider between 2 sections
private static final float DIVIDER_ANGLE = 7;
public static final float DEGREES_IN_CIRCLE = 360;
public static final int PADDING = 18;
public static final int PADDING2 = 12;
protected final Paint paint = new Paint();
protected final Paint waitingPaint = new Paint();
protected final Paint backgroundPaint = new Paint();
private int totalSections = 5;
private int fullSections = 2;
private int waiting = 3; // The outer ring. You can omit this
private RectF rect = new RectF();
public RoundedSectionProgressBar(Context context) {
super(context);
init(context, null);
}
public RoundedSectionProgressBar(Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
init(context, attrs);
}
public RoundedSectionProgressBar(Context context, #Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context, attrs);
}
private void init(Context context, AttributeSet attrs) {
// Can come from attrs if need be?
int strokeWidth = 3;
setupPaint(context, strokeWidth, paint, R.color.filled_color_inner_ring);
setupPaint(context, strokeWidth, waitingPaint, R.color.empty_color_inner_ring);
setupPaint(context, strokeWidth, backgroundPaint, R.color.filled_color_outer_ring);
}
private void setupPaint(Context context, int strokeWidth, Paint backgroundPaint, int colorRes) {
backgroundPaint.setStrokeCap(Paint.Cap.SQUARE);
backgroundPaint.setColor(context.getResources().getColor(colorRes));
backgroundPaint.setAntiAlias(true);
backgroundPaint.setStrokeWidth(strokeWidth);
backgroundPaint.setStyle(Paint.Style.STROKE);
}
public int getTotalSections() {
return totalSections;
}
public void setTotalSections(int totalSections) {
this.totalSections = totalSections;
invalidate();
}
public int getFullSections() {
return fullSections;
}
public void setNumberOfSections(int fullSections, int totalSections, int waiting) {
this.fullSections = fullSections;
this.totalSections = totalSections;
this.waiting = waiting;
invalidate();
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
rect.set(getLeft() + PADDING, getTop() + PADDING, getRight() - PADDING, getBottom() - PADDING);
float angleOfSection = (DEGREES_IN_CIRCLE / totalSections) - DIVIDER_ANGLE;
// Drawing the inner ring
for (int i = 0; i < totalSections; i++) {
// -90 because it doesn't start at the top, so rotate by -90
// divider_angle/2 especially in 2 sections, it's visibly rotated by Divider angle, so we split this between last and first
float startAngle = -90 + i * (angleOfSection + DIVIDER_ANGLE) + DIVIDER_ANGLE / 2;
if (i < fullSections) {
canvas.drawArc(rect, startAngle, angleOfSection, false, paint);
} else {
canvas.drawArc(rect, startAngle, angleOfSection, false, backgroundPaint);
}
}
// Drawing the outer ring
rect.set(getLeft() + PADDING2, getTop() + PADDING2, getRight() - PADDING2, getBottom() - PADDING2);
for (int i = 0; i < waiting; i++) {
float startAngle = -90 + i * (angleOfSection + DIVIDER_ANGLE) + DIVIDER_ANGLE / 2;
canvas.drawArc(rect, startAngle, angleOfSection, false, waitingPaint);
}
}
}
Notice that this code won't give you the outer ring's 'empty' slots, since we decided against them in the end. The inner circle will have both the empty and filled slots. The whole class can be reused, and it's responsible just for the 2 rings that are drawn, the 6/6, +3 and the red circle are parts of another view.
The most important piece of the code is the onDraw method. It contains the logic for drawing the arcs in the for loop, as well as the logic for calculating the angles and adding spaces between them. Everything is rotated by -90 degrees, because I needed it to start at the top, rather than on the right, as it is the 0-degree angle in Android. It's not that complex, and you can modify it to fit your needs better should you need to.

I find it easier to do math for drawArc(operating on angle values based on number of sections) rather than computing the arc length.
Here's a quick idea, with a lot of hard-coded properties, but you should be able to get the idea:
public class MyStrokeCircleView extends View {
private Paint mPaint;
private RectF mRect;
private int mPadding;
private int mSections;
private int mFullArcSliceLength;
private int mColorArcLineLength;
private int mArcSectionGap;
public MyStrokeCircleView(Context context) {
super(context);
init(null, 0);
}
public MyStrokeCircleView(Context context, AttributeSet attrs) {
super(context, attrs);
init(attrs, 0);
}
public MyStrokeCircleView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(attrs, defStyle);
}
private void init(AttributeSet attrs, int defStyle) {
mPaint = new Paint();
mPaint.setFlags(Paint.ANTI_ALIAS_FLAG);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeWidth(10);
mPaint.setColor(ContextCompat.getColor(getContext(), android.R.color.darker_gray));
mPadding = 5;
mRect = new RectF(mPadding, mPadding, mPadding, mPadding);
mSections = 4;
mFullArcSliceLength = 360 / mSections;
mArcSectionGap = mFullArcSliceLength / 10;
mColorArcLineLength = mFullArcSliceLength - 2 * mArcSectionGap;
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mRect.right = getWidth() - mPadding;
mRect.bottom = getHeight() - mPadding;
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (int i = 0; i < mSections; i++) {
canvas.drawArc(mRect, i * mFullArcSliceLength + mArcSectionGap, mColorArcLineLength, false, mPaint);
}
}
}

EditText's onDraw canvas gets shifted to the left when single line is set

I have a very simple customized EditText like this:
public class MyEditText extends EditText {
private Paint mPaint;
public MyEditText(Context context) {
super(context);
init();
}
public MyEditText(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public MyEditText(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
setSingleLine();
mPaint = new Paint();
mPaint.setColor(Color.RED);
mPaint.setStrokeWidth(6);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int y = canvas.getHeight() * 6 / 7;
canvas.drawLine(0, y, canvas.getWidth(), y, mPaint);
}
}
As I set single line mode on, when text is short everything is fine, it would look like this:
But once the text gets longer (more than width of the EditText), the red line is shifted to the left like this:
As you'll probably notice I used 0 and canvas.getWidth() to connect both sides of the view, but the line gets shifted, so doesn't it mean the whole canvas gets shifted as well?
If so it's such a strange behavior that I didn't expect from a View descendant. Can someone shed me some light on this strange behavior?
Thanks

Change your onDraw() method like below...
#Override
protected void onDraw(Canvas canvas) {
Rect r = new Rect();
int baseline = getLineBounds(0, r);
int y = canvas.getHeight() * 6 / 7;
canvas.drawLine(r.left, y, r.right, y, mPaint);
super.onDraw(canvas);
}

I want to follow the path of drawing dynamic curve,how to solve it?

1、Here is the chart:
2、Here is the code:
private void drawCircle( Canvas canvas, String content ){
mPath.addCircle(getWidth() / 2, getHeight() / 2, mRadius, Direction.CCW);
canvas.rotate(180, getWidth() / 2, getHeight() / 2);
canvas.drawTextOnPath(content, mPath, 0, 0, mPaint);
}
3、My problem is how to let the circle one point one point display，Not all one-time display。I'm try to use Handler/Thread/Timer to draw a dynamic chart by drawTextOnPath and drawPath method, but there show nothing.

You need to use postDelayed() and add a new character each time.
public class MyView extends View {
private Path mPath = new Path();
private float mRadius = 100;
private Paint mPaint = new Paint();
private String theWholeText = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
private String theCurrentText = "";
private int i = 0;
private long frequency = 150;
private Runnable addCharacter = new Runnable() {
#Override
public void run() {
theCurrentText = theWholeText.substring(0, ++i);
invalidate();
}
};
public MyView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mPaint.setColor(Color.RED);
mPaint.setTextSize(20);
}
public MyView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public MyView(Context context) {
this(context, null, 0);
}
private void drawCircle(Canvas canvas, String content) {
mPath.addCircle(getWidth() / 2, getHeight() / 2, mRadius, Path.Direction.CCW);
canvas.rotate(180, getWidth() / 2, getHeight() / 2);
canvas.drawTextOnPath(content, mPath, 0, 0, mPaint);
}
#Override
protected void onDraw(Canvas canvas) {
drawCircle(canvas, theCurrentText);
if (theCurrentText.length() < theWholeText.length())
postDelayed(addCharacter, frequency);
}
}
Please mark as correct answer if that works out for you!

Prevent ImageView redraw state after hide keyboard

First, I have a view like this:
When user press some text in edittext, I try to draw some rectangles in ImageView with specific coordinates. The problem is when the soft keyboard is hidden, all draw state of Imageview display wrong coordinates, look like it invalidated the imageview. I wonder is there any way to stop this.
Here is my Custom Drawable Imageview:
public class DrawableImageView extends ImageView {
private Paint ptBlur;
private List<Rect> rects;
private int originWidth;
private int originHeight;
public DrawableImageView(Context context) {
super(context);
initPaint();
}
public DrawableImageView(Context context, AttributeSet attrs) {
super(context, attrs);
initPaint();
}
public DrawableImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initPaint();
}
public void setRects(List<Rect> rects, int originWidth, int originHeight) {
this.originHeight = originHeight;
this.originWidth = originWidth;
this.rects = rects;
invalidate();
}
private void initPaint() {
ptBlur = new Paint();
ptBlur.setColor(Color.YELLOW);
ptBlur.setStyle(Paint.Style.STROKE);
ptBlur.setStrokeWidth(5);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (rects != null) {
int width = getWidth();
int height = getHeight();
for (Rect rect : rects) {
rect.bottom = Math.round(height * rect.bottom / originHeight);
rect.left = Math.round(width * rect.left / originWidth);
rect.right = Math.round(width * rect.right / originWidth);
rect.top = Math.round(height * rect.top / originHeight);
canvas.drawRect(rect, ptBlur);
}
}
}
}
The OnEditorActionListener for EditText:
// get the rectangles and draw
List<Rect> rects = DataUtil.getHighlightRectList(searchText);
drawableImageView.setRects(rects, pageWidth, pageHeight);