Example usage for android.graphics Canvas saveLayer

Introduction

In this page you can find the example usage for android.graphics Canvas saveLayer.

Prototype

public int saveLayer(@Nullable RectF bounds, @Nullable Paint paint, @Saveflags int saveFlags)

Source Link

Document

This behaves the same as save(), but in addition it allocates and redirects drawing to an offscreen bitmap.

Usage

From source file:com.raghu.test.widgets.BezelImageView.java

@SuppressLint("WrongConstant")
@Override//w w w .j  ava 2 s  .c o m
protected void onDraw(Canvas canvas) {
    if (mBounds == null) {
        return;
    }

    int width = mBounds.width();
    int height = mBounds.height();

    if (width == 0 || height == 0) {
        return;
    }

    if (!mCacheValid || width != mCachedWidth || height != mCachedHeight || isSelected != isPressed) {
        // Need to redraw the cache
        if (width == mCachedWidth && height == mCachedHeight) {
            // Have a correct-sized bitmap cache already allocated. Just erase it.
            mCacheBitmap.eraseColor(0);
        } else {
            // Allocate a new bitmap with the correct dimensions.
            mCacheBitmap.recycle();
            //noinspection AndroidLintDrawAllocation
            mCacheBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
            mCachedWidth = width;
            mCachedHeight = height;
        }

        Canvas cacheCanvas = new Canvas(mCacheBitmap);
        if (mMaskDrawable != null) {
            int sc = cacheCanvas.save();
            mMaskDrawable.draw(cacheCanvas);
            if (isSelected) {
                if (mSelectorFilter != null) {
                    mMaskedPaint.setColorFilter(mSelectorFilter);
                } else {
                    mMaskedPaint.setColorFilter(mDesaturateColorFilter);

                }
            } else {
                mMaskedPaint.setColorFilter(null);
            }
            cacheCanvas.saveLayer(mBoundsF, mMaskedPaint,
                    Canvas.HAS_ALPHA_LAYER_SAVE_FLAG | Canvas.FULL_COLOR_LAYER_SAVE_FLAG);
            super.onDraw(cacheCanvas);
            cacheCanvas.restoreToCount(sc);
        } else if (isSelected) {
            int sc = cacheCanvas.save();
            cacheCanvas.drawRect(0, 0, mCachedWidth, mCachedHeight, mBlackPaint);
            if (mSelectorFilter != null) {
                mMaskedPaint.setColorFilter(mSelectorFilter);
            } else {
                mMaskedPaint.setColorFilter(mDesaturateColorFilter);
            }
            cacheCanvas.saveLayer(mBoundsF, mMaskedPaint,
                    Canvas.HAS_ALPHA_LAYER_SAVE_FLAG | Canvas.FULL_COLOR_LAYER_SAVE_FLAG);
            super.onDraw(cacheCanvas);
            cacheCanvas.restoreToCount(sc);
        } else {
            super.onDraw(cacheCanvas);
        }
    }

    // Draw from cache
    canvas.drawBitmap(mCacheBitmap, mBounds.left, mBounds.top, null);

    //remember the previous press state
    isPressed = isPressed();
}