在 Canvas 中绘制位图的帧速率更高（第 2 部分）？
这就是我想要做的：我正在尝试加载一系列位图来显示动画。这意味着我需要有下降 fps（24 fps）。我需要加载不超过 10 秒的动画或大约 300 个位图。由于它是动态壁纸，我只能手动绘制每一帧。
这是我到目前为止所尝试的：
- 明显的策略：每帧加载每个位图并绘制它。这很慢。
- 使用缓存。我将位图加载放在单独的线程中。大约 20 个位图的缓存在后台持续加载。然而，我的性能仍然很差（大约 10 fps）。罪魁祸首是位图加载缓慢。
- 我本来打算尝试使用 OpenGL，但后来我意识到即使使用 OpenGL，位图加载缓慢仍然是一个问题。正确的？ （或者我错了？）
那么我还可以使用哪些其他策略？
这就是我的想法：如果我使用 openGL，我可以使用较小的位图（因为它可以提供更好的缩放效果）。也许那时我可以拥有更大的缓存 - 比如说也许 3 秒。有了更大的缓存，位图加载慢就不会成为问题了，对吗？
还有其他策略吗？
哦，这是我当前的位图加载函数：
void loadNthBitmap(int i, int n) {
try {
buf = new
BufferedInputStream(assets.
open(folder+"/"
+imageList[n])
);
tmpBitmap = BitmapFactory.
decodeStream(buf);
rbitmap[i] = Bitmap.createBitmap
(tmpBitmap,
0,0,imageWidth,imageHeight,
transMatrix,false);
}
catch(IOException e) {}
}
其中 imageList 是预定义的资源列表，transMatrix 是旋转和缩放矩阵。
Here's what I'm trying to do: I'm trying to load a sequence of bitmaps to display an animation. That means that I need to have a descent fps (24 fps). I need to load no more than 10 seconds of animations or about 300 bitmaps. And since it's a live wallpaper I'm limited to manually drawing each frame.
Here's what I tried so far:
- The obvious strategy: load each bitmap each frame and draw it. This is slow.
- Use caching. I put the bitmap loading in a seperate thread. A cache of about 20 bitmaps continously load in the background. However, I still get poor performance (about 10 fps). The culprit is slow bitmap loading.
- I was going to try using OpenGL but then I realized that even with OpenGL, the slow bitmap loading will still be a problem. Right? (Or am I wrong?)
So what other strategies can I use?
Here's what I had in mind: if I use openGL, I can use smaller bitmaps (because it gives better scaling). Perhaps then I can have a bigger cache - say perhaps 3 seconds. With a larger cache, the slow bitmap loading will not be a problem, right?
Any other strategies?
Oh and this is my current bitmap loading function:
void loadNthBitmap(int i, int n) {
try {
buf = new
BufferedInputStream(assets.
open(folder+"/"
+imageList[n])
);
tmpBitmap = BitmapFactory.
decodeStream(buf);
rbitmap[i] = Bitmap.createBitmap
(tmpBitmap,
0,0,imageWidth,imageHeight,
transMatrix,false);
}
catch(IOException e) {}
}
where imageList is pre-defined list of assets and transMatrix is a rotation and scaling matrix.
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评论（1）
您想要做的事情（即全帧动画）并不容易。几乎所有 Android 动画（从 SDK 中的月球着陆器示例到《愤怒的小鸟》）都是由在相对静态的背景上移动的小精灵组成。
解决您的问题的“明显”解决方案是将您的动画转换为 mpeg，然后将其解码为视频动态壁纸，复制此人在此采用的方法： http://forum.xda-developers.com/showthread.php?t=804720（替代链接 http://android.ccpcreations.com/vlw/)
What you're trying to do (i.e. full-frame animation) is not easy. Almost all Android animation (from the Lunar Lander example in the SDK to Angry Birds) consists of moving small sprites on a relatively static background.
The "obvious" solution to your problem would be to turn your animation into an mpeg and then decode it as a video live wallpaper, replicating the approach that this guy took here: http://forum.xda-developers.com/showthread.php?t=804720 (alternative link http://android.ccpcreations.com/vlw/)