Android Canvas 保存为图片-优快云博客

本文探讨了在Android应用中通过Bitmap缓存优化DrawView的绘制效率的方法，详细介绍了如何创建内存中的图片、配置画笔以及利用缓存减少重复绘制操作，从而提升用户体验。

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-------Activity.java

File f = new File("/sdcard/qianming.jpg");
FileOutputStream fos = null;
try {
fos = new FileOutputStream(f);
dv.cacheBitmap.compress(Bitmap.CompressFormat.JPEG, 50, fos);

} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

--------------DrawView.java

float preX;
float preY;
private Path path;
public Paint paint = null;
final int VIEW_WIDTH = 1024;
final int VIEW_HEIGHT = 1024;
// 定义一个内存中的图片，该图片将作为缓冲区
Bitmap cacheBitmap = null;
// 定义cacheBitmap上的Canvas对象
Canvas cacheCanvas = null;

public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
cacheBitmap = Bitmap.createBitmap(VIEW_WIDTH, VIEW_HEIGHT,
Config.ARGB_8888);
cacheCanvas = new Canvas();
path = new Path();
// 设置cacheCanvas将会绘制到内存中的cacheBitmap上
cacheCanvas.setBitmap(cacheBitmap);
// 设置画笔的颜色
paint = new Paint(Paint.DITHER_FLAG);
paint.setColor(Color.RED);
// 设置画笔风格
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(4);
// 反锯齿
paint.setAntiAlias(true);
paint.setDither(true);
cacheCanvas.save(Canvas.ALL_SAVE_FLAG );
cacheCanvas.restore();