1. ImageView 绘制图片
这个想必做过Android开发的都知道如何去绘制了。很简单:
Bitmap bitmap = BitmapFactory.decodeFile(Environment.getExternalStorageDirectory().getPath() + File.separator + "11.jpg"); imageView.setImageBitmap(bitmap);
很轻松,在界面上看到了我们绘制的图片。
2. 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) { } });
3. 自定义 View 绘制图片
这个有绘制自定义View经验的可以很轻松的完成,本人也简单整理过 Android 自定义 View 绘制 这一块的知识:
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); } } }
注:别忘记了权限,否则是不会展示成功的。
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>