Android 音视频开发序列1---通过三种方式绘制图片
一、ImageView 绘制图片
Bitmap bitmap = BitmapFactory.decodeFile(Environment.getExternalStorageDirectory().getPath() + File.separator + "11.jpg");
imageView.setImageBitmap(bitmap);
二、SurfaceView 绘制图片
这个比 ImageView 绘制图片稍微复杂一点点:
SurfaceView surfaceView = (SurfaceView) findViewById(R.id.surface);
surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
if (surfaceHolder == null) {
return;
}
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setStyle(Paint.Style.STROKE);
Bitmap bitmap = BitmapFactory.decodeFile(Environment.getExternalStorageDirectory().getPath() + File.separator + "11.jpg"); // 获取bitmap
Canvas canvas = surfaceHolder.lockCanvas(); // 先锁定当前surfaceView的画布
canvas.drawBitmap(bitmap, 0, 0, paint); //执行绘制操作
surfaceHolder.unlockCanvasAndPost(canvas); // 解除锁定并显示在界面上
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
}
});
三、自定义 View 绘制图片
public class CustomView extends View {
Paint paint = new Paint();
Bitmap bitmap;
public CustomView(Context context) {
super(context);
paint.setAntiAlias(true);
paint.setStyle(Paint.Style.STROKE);
bitmap = BitmapFactory.decodeFile(Environment.getExternalStorageDirectory().getPath() + File.separator + "11.jpg"); // 获取bitmap
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 不建议在onDraw做任何分配内存的操作
if (bitmap != null) {
canvas.drawBitmap(bitmap, 0, 0, paint);
}
}
}
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>