在自定义视图onDraw中使用硬件层

Question

因此,我试图了解如何在View持久动画的自定义中正确使用硬件加速(如果可用).这是我的基本前提onDraw():

canvas.drawColor(mBackgroundColor);

for (Layer layer : mLayers) {
    canvas.save();
    canvas.translate(layer.x, layer.y);

    //Draw that number of images in a grid, offset by -1
    for (int i = -1; i < layer.xCount - 1; i++) {
        for (int j = -1; j < layer.yCount - 1; j++) {
            canvas.drawBitmap(layer.bitmap, layer.w * i, layer.h * j, null);
        }
    }

    //If the layer's x has moved past its width, reset back to a seamless position
    layer.x += ((difference * layer.xSpeed) / 1000f);
    float xOverlap = layer.x % layer.w;
    if (xOverlap > 0) {
        layer.x = xOverlap;
    }

    //If the layer's y has moved past its height, reset back to a seamless position
    layer.y += ((difference * layer.ySpeed) / 1000f);
    float yOverlap = layer.y % layer.h;
    if (yOverlap > 0) {
        layer.y = yOverlap;
    }

    canvas.restore();
}

//Redraw the view
ViewCompat.postInvalidateOnAnimation(this);

我正在启用硬件层onAttachedToWindow()并禁用它们onDetachedFromWindow(),但我试图了解我是否真正使用它.从本质上讲,i/j调用的循环drawBitmap()永远不会改变; 唯一改变的是Canvas翻译.是Bitmap自动保存到GPU后面的纹理,还是我需要手动执行此操作？

Answer 1

您View.LAYER_TYPE_HARDWARE准确设置了哪些视图？如果要在包含上面显示的绘图代码的视图上设置硬件层,则会导致系统执行大量必要的工作.由于您只是绘制位图,因此您无需在此处执行任何操作.如果您调用Canvas.drawBitmap()框架将代表您缓存生成的OpenGL纹理.

但是,您可以更多地优化代码.drawBitmap()您可以使用子视图,而不是调用.如果使用offset*()方法(或setX()/ setY())移动这些子项,框架将应用进一步的优化以避免draw()再次调用方法.

通常,应该在视图上设置硬件图层,这些视图的绘制成本很高,而且其内容不会经常更改(所以与您正在做的事情完全相反:)