android.view.Surface#lockCanvas ( )源码实例Demo

@RequiresApi(api = Build.VERSION_CODES.KITKAT)
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    Surface surface = holder.getSurface();
    if (surface == null)
        return;

    try {
        Method setSharedBufferMode = Surface.class.getMethod("setSharedBufferMode", boolean.class);
        setSharedBufferMode.invoke(surface, true);
        displayMessage("Using shared buffer mode.");
    } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
        displayMessage("Shared buffer mode is not supported.");
    }
    Canvas canvas = surface.lockCanvas(null);
    canvas.drawColor(Color.GRAY);
    surface.unlockCanvasAndPost(canvas);
}
 

/**
 * Clears the surface, then draws a filled circle with a shadow.
 * <p>
 * The Canvas drawing we're doing may not be fully implemented for hardware-accelerated
 * renderers (shadow layers only supported for text).  However, Surface#lockCanvas()
 * currently only returns an unaccelerated Canvas, so it all comes out looking fine.
 */
private void drawCircleSurface(Surface surface, int x, int y, int radius) {
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.WHITE);
    paint.setStyle(Paint.Style.FILL);
    paint.setShadowLayer(radius / 4 + 1, 0, 0, Color.RED);

    Canvas canvas = surface.lockCanvas(null);
    try {
        Log.v(TAG, "drawCircleSurface: isHwAcc=" + canvas.isHardwareAccelerated());
        canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
        canvas.drawCircle(x, y, radius, paint);
    } finally {
        surface.unlockCanvasAndPost(canvas);
    }
}
 

/**
 * Clears the surface, then draws a filled circle with a shadow.
 * <p>
 * The Canvas drawing we're doing may not be fully implemented for hardware-accelerated
 * renderers (shadow layers only supported for text).  However, Surface#lockCanvas()
 * currently only returns an unaccelerated Canvas, so it all comes out looking fine.
 */
private void drawCircleSurface(Surface surface, int x, int y, int radius) {
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.WHITE);
    paint.setStyle(Paint.Style.FILL);
    paint.setShadowLayer(radius / 4 + 1, 0, 0, Color.RED);

    Canvas canvas = surface.lockCanvas(null);
    try {
        Log.v(TAG, "drawCircleSurface: isHwAcc=" + canvas.isHardwareAccelerated());
        canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
        canvas.drawCircle(x, y, radius, paint);
    } finally {
        surface.unlockCanvasAndPost(canvas);
    }
}
 

private void tryLoadBitmap() {
    if(mBitmap != null && getInputHolder().getSurface() != null) {
        SurfaceTexture st = getInputHolder().getSurfaceTexture();
        Surface s = getInputHolder().getSurface();

        // First set the texture resolution
        st.setDefaultBufferSize(mBitmap.getWidth(), mBitmap.getHeight());

        // Then draw the image data
        Canvas c = s.lockCanvas(null);
        c.drawBitmap(mBitmap, 0, 0, null);
        s.unlockCanvasAndPost(c);
    }
}
 

public void setRectColor(int color) {
    Surface surface = getHolder().getSurface();
    if (surface == null || !isActive)
        return;
    Rect rect = new Rect(10, 10, 310, 310);
    Canvas canvas = surface.lockCanvas(rect);
    Paint paint = new Paint();
    paint.setColor(color);
    canvas.drawRect(rect, paint);
    surface.unlockCanvasAndPost(canvas);
}
 

/**
 * Clears the surface, then draws a filled circle with a shadow.
 * <p>
 * Similar to drawCircleSurface(), but the position changes based on the value of "i".
 */
private void drawBouncingCircle(Surface surface, int i) {
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.WHITE);
    paint.setStyle(Paint.Style.FILL);

    Canvas canvas = surface.lockCanvas(null);
    try {
        Trace.beginSection("drawBouncingCircle");
        Trace.beginSection("drawColor");
        canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
        Trace.endSection(); // drawColor

        int width = canvas.getWidth();
        int height = canvas.getHeight();
        int radius, x, y;
        if (width < height) {
            // portrait
            radius = width / 4;
            x = width / 4 + ((width / 2 * i) / BOUNCE_STEPS);
            y = height * 3 / 4;
        } else {
            // landscape
            radius = height / 4;
            x = width * 3 / 4;
            y = height / 4 + ((height / 2 * i) / BOUNCE_STEPS);
        }

        paint.setShadowLayer(radius / 4 + 1, 0, 0, Color.RED);

        canvas.drawCircle(x, y, radius, paint);
        Trace.endSection(); // drawBouncingCircle
    } finally {
        surface.unlockCanvasAndPost(canvas);
    }
}
 

/**
 * Clears the surface, then draws a filled circle with a shadow.
 * <p>
 * Similar to drawCircleSurface(), but the position changes based on the value of "i".
 */
private void drawBouncingCircle(Surface surface, int i) {
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.WHITE);
    paint.setStyle(Paint.Style.FILL);

    Canvas canvas = surface.lockCanvas(null);
    try {
        Trace.beginSection("drawBouncingCircle");
        Trace.beginSection("drawColor");
        canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
        Trace.endSection(); // drawColor

        int width = canvas.getWidth();
        int height = canvas.getHeight();
        int radius, x, y;
        if (width < height) {
            // portrait
            radius = width / 4;
            x = width / 4 + ((width / 2 * i) / BOUNCE_STEPS);
            y = height * 3 / 4;
        } else {
            // landscape
            radius = height / 4;
            x = width * 3 / 4;
            y = height / 4 + ((height / 2 * i) / BOUNCE_STEPS);
        }

        paint.setShadowLayer(radius / 4 + 1, 0, 0, Color.RED);

        canvas.drawCircle(x, y, radius, paint);
        Trace.endSection(); // drawBouncingCircle
    } finally {
        surface.unlockCanvasAndPost(canvas);
    }
}
 

@Override
public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int width, int height) {
	final Surface surface = new Surface(surfaceTexture);
	final Canvas canvas = surface.lockCanvas(null);
	mDrawer.onDrawPlaceholder(canvas);
	surface.unlockCanvasAndPost(canvas);
	surface.release();
}
 

/**
 * Draw color bars with text labels.
 */
private void drawColorBars(Surface surface) {
    Canvas canvas = surface.lockCanvas(null);
    try {
        // TODO: if the device is in portrait, draw the color bars horizontally.  Right
        // now this only looks good in landscape.
        int width = canvas.getWidth();
        int height = canvas.getHeight();
        int least = Math.min(width, height);

        Log.d(TAG, "Drawing color bars at " + width + "x" + height);

        Paint textPaint = new Paint();
        Typeface typeface = Typeface.defaultFromStyle(Typeface.NORMAL);
        textPaint.setTypeface(typeface);
        textPaint.setTextSize(least / 20);
        textPaint.setAntiAlias(true);

        Paint rectPaint = new Paint();
        for (int i = 0; i < 8; i++) {
            int color = 0xff000000;
            if ((i & 0x01) != 0) {
                color |= 0x00ff0000;
            }
            if ((i & 0x02) != 0) {
                color |= 0x0000ff00;
            }
            if ((i & 0x04) != 0) {
                color |= 0x000000ff;
            }
            rectPaint.setColor(color);

            float sliceWidth = width / 8;
            canvas.drawRect(sliceWidth * i, 0, sliceWidth * (i+1), height, rectPaint);
        }
        rectPaint.setColor(0x80808080);     // ARGB 50/50 grey (non-premul)
        float sliceHeight = height / 8;
        int posn = 6;
        canvas.drawRect(0, sliceHeight * posn, width, sliceHeight * (posn+1), rectPaint);

        // Draw the labels last so they're on top of everything.
        for (int i = 0; i < 8; i++) {
            drawOutlineText(canvas, textPaint, COLOR_NAMES[i],
                    (width / 8) * i + 4, (height / 8) * ((i & 1) + 1));
        }
    } finally {
        surface.unlockCanvasAndPost(canvas);
    }
}