Android 音视频开发序列1-优快云博客

本文链接：https://blog.youkuaiyun.com/zouhaicheng/article/details/114905315

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"/>