用画布绘制Android

现在我想画布画出一个颜色。用画布绘制Android

public class AndroidTentaTestActivity extends Activity { 

    private Bitmap bm; 
    private Canvas c; 

    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     this.setContentView(R.layout.main); 

     bm = Bitmap.createBitmap(100, 100, Config.ARGB_8888); 
     c = new Canvas(bm); 
     c.drawARGB(100, 0, 0, 150); 
    } 
}

上面的代码是我到目前为止写的，显然不起作用。我怀疑Bitmap不知道怎么连接到我正在做的事情上，但我不知道如何解决它。我如何？

来源

2013-01-01 Zacharias Hortén

什么* *究竟是你想怎么办？ “不知何故未连接”。你什么意思？除非你在某处显示位图，当然你不会看到它。 – Simon

画布不显示，因此整个屏幕都是黑色的（在我用于调试的s2上）。我如何显示画布？ –

你还没有解释你想做什么。您无法“显示”画布。画布只是一个在位图上绘制调用的持有者。除非您在画布上绘制属于您的用户界面的位图，否则您将看不到任何内容。 – Simon

在mPaint.setColor（）中更改所需的颜色。

public class AndroidTentaTestActivity extends AppCompatActivity { 

MyView mv; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 


    mv = new MyView(this); 
    mv.setDrawingCacheEnabled(true); 
    setContentView(mv); 

    mPaint = new Paint(); 
    mPaint.setAntiAlias(true); 
    mPaint.setDither(true); 
    mPaint.setColor(0xFFFF0000); 
} 

private Paint mPaint; 

@Override 
public void onClick(View v) { 

} 

public class MyView extends View { 

    private Bitmap mBitmap; 
    private Canvas mCanvas; 
    private Path mPath; 
    private Paint mBitmapPaint; 
    Context context; 

    public MyView(Context c) { 
     super(c); 
     context = c; 
     mPath = new Path(); 
     mBitmapPaint = new Paint(Paint.DITHER_FLAG); 

    } 

    @Override 
    protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
     super.onSizeChanged(w, h, oldw, oldh); 
     mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888); 
     mCanvas = new Canvas(mBitmap); 

    } 


    @Override 
    protected void onDraw(Canvas canvas) { 
     super.onDraw(canvas); 
     canvas.drawColor(0xFFFFFFFF); 
     canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint); 
     canvas.drawPath(mPath, mPaint); 
    } 

    private float mX, mY; 
    private static final float TOUCH_TOLERANCE = 1; 

    private void touch_start(float x, float y) { 
     //showDialog(); 
     mPath.reset(); 
     mPath.moveTo(x, y); 

     mX = x; 
     mY = y; 

    } 

    private void touch_move(float x, float y) { 
     float dx = Math.abs(x - mX); 
     float dy = Math.abs(y - mY); 
     if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) { 
      // mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);      //2,2.old values 

      mX = x; 
      mY = y; 
     } 

    } 

    private void touch_up() { 
     mPath.lineTo(mX, mY); 
     // commit the path to our offscreen 
     mCanvas.drawPath(mPath, mPaint); 

     // kill this so we don't double draw 
     mPath.reset(); 

    } 

    @Override 
    public boolean onTouchEvent(MotionEvent event) { 

     float x = event.getX(); 
     float y = event.getY(); 

     switch (event.getAction()) { 
      case MotionEvent.ACTION_DOWN: 
       touch_start(x, y); 
       invalidate(); 
       break; 
      case MotionEvent.ACTION_MOVE: 

       touch_move(x, y); 
       invalidate(); 
       break; 
      case MotionEvent.ACTION_UP: 
       touch_up(); 
       invalidate(); 
       break; 
     } 
     return true; 
    } 
}

来源

2016-05-31 06:03:26 onexf

LinearLayout ll = (LinearLayout) findViewById(R.id.rect); 
Paint paint = new Paint(); 
paint.setColor(Color.parseColor("#CD5C5C")); 
Bitmap bg = Bitmap.createBitmap(ll.getWidth(),ll.getHeight() , Bitmap.Config.ARGB_8888); 
Canvas canvas = new Canvas(bg); 
canvas.drawARGB(200, 0, 225, 255); 
ll.setBackgroundDrawable(new BitmapDrawable(bg));

来源

2016-05-31 09:27:53

用画布绘制Android

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