2010-08-17 91 views
1

我现在研究了几小时的Android参考,但并没有真正了解如何在ImageView上绘制某些东西(文本,位图,路径....)。在ImageView上绘制

我应该扩展查看并使用onDraw() -Method?如果是的话,我该如何在我的ImageView上绘图?

或者还有其他方法可以实现我的目标吗?

回答

4

如果您只是想在您的ImageView上绘制另一个位图,并且它不应该是动态的,那么要使用AbsoluteLayout并将它们放在彼此之上。

如果它应该更加动态,我推荐使用SurfaceView。该教程可以在这里找到:(通过webarchive目前只有在线:http://web.archive.org/web/20121005111921/http://www.droidnova.com/2d-tutorial-serieshttp://www.droidnova.com/playing-with-graphics-in-android-part-i,147.html

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感谢您阅读本教程,我将阅读它。 – Alien 2010-08-17 15:03:15

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嗯....他也没有在他的SurfaceView下有东西,但我不想有ImageView,也不想在它上面动态地绘制文本。任何想法如何实现? – Alien 2010-08-17 15:48:04

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你没读过这个系列的所有部分,对吧?忘记ImageView并在SurfaceView上绘制位图。在此之上绘制您的文字。只要阅读至少前三部分! – WarrenFaith 2010-08-18 08:53:16

0

SurfaceView是你想要的。它会给你一个Canvas物体,你可以使用canvas.drawCircle(...)canvas.drawText(...),canvas.drawBitamp(...)来绘制物体。

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好的,谢谢,我会读参考SurfaceView,然后我认为我将能够实现我的目标 – Alien 2010-08-17 15:04:04

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如何在SurfaceView下使用ImageView(在基于XML的布局中声明),以便我可以绘制它? – Alien 2010-08-17 15:47:02

3

是的,你可以使用onDraw方法。有一个传入该方法的Canvas对象,您将使用该对象在视图上绘制。这里是一个如何去做的例子...来自Zebra Crossing条码扫描器应用程序。这是显示黑色外框,红色扫描仪线和黄色扫描结果点的视图。

@Override 
public void onDraw(Canvas canvas) { 
    Rect frame = CameraManager.get().getFramingRect(); 
    if (frame == null) { 
     return; 
    } 
    int width = canvas.getWidth(); 
    int height = canvas.getHeight(); 
    Log.v("ViewfinderView", "Canvas size: " + width + ", " + height); 

    // Draw the exterior (i.e. outside the framing rect) darkened 
    paint.setColor(resultBitmap != null ? resultColor : maskColor); 
    canvas.drawRect(0, 0, width, frame.top, paint); 
    canvas.drawRect(0, frame.top, frame.left, frame.bottom + 1, paint); 
    canvas.drawRect(frame.right + 1, frame.top, width, frame.bottom + 1, paint); 
    canvas.drawRect(0, frame.bottom + 1, width, height, paint); 

    if (resultBitmap != null) { 
     // Draw the opaque result bitmap over the scanning rectangle 
     paint.setAlpha(OPAQUE); 
     canvas.drawBitmap(resultBitmap, frame.left, frame.top, paint); 
    } else { 

     // Draw a two pixel solid black border inside the framing rect 
     paint.setColor(frameColor); 
     canvas.drawRect(frame.left, frame.top, frame.right + 1, frame.top + 2, paint); 
     canvas.drawRect(frame.left, frame.top + 2, frame.left + 2, frame.bottom - 1, paint); 
     canvas.drawRect(frame.right - 1, frame.top, frame.right + 1, frame.bottom - 1, paint); 
     canvas.drawRect(frame.left, frame.bottom - 1, frame.right + 1, frame.bottom + 1, paint); 

     // Draw a red "laser scanner" line through the middle to show decoding is active 
     paint.setColor(laserColor); 
     paint.setAlpha(SCANNER_ALPHA[scannerAlpha]); 
     scannerAlpha = (scannerAlpha + 1) % SCANNER_ALPHA.length; 
     int middle = frame.height()/2 + frame.top; 
     canvas.drawRect(frame.left + 2, middle - 1, frame.right - 1, middle + 2, paint); 

     Collection<ResultPoint> currentPossible = possibleResultPoints; 
     Collection<ResultPoint> currentLast = lastPossibleResultPoints; 
     if (currentPossible.isEmpty()) { 
     lastPossibleResultPoints = null; 
     } else { 
     possibleResultPoints = new HashSet<ResultPoint>(5); 
     lastPossibleResultPoints = currentPossible; 
     paint.setAlpha(OPAQUE); 
     paint.setColor(resultPointColor); 
     for (ResultPoint point : currentPossible) { 
      canvas.drawCircle(frame.left + point.getX(), frame.top + point.getY(), 6.0f, paint); 
     } 
     } 
     if (currentLast != null) { 
     paint.setAlpha(OPAQUE/2); 
     paint.setColor(resultPointColor); 
     for (ResultPoint point : currentLast) { 
      canvas.drawCircle(frame.left + point.getX(), frame.top + point.getY(), 3.0f, paint); 
     } 
     } 

     // Request another update at the animation interval, but only repaint the laser line, 
     // not the entire viewfinder mask. 
     postInvalidateDelayed(ANIMATION_DELAY, frame.left, frame.top, frame.right, frame.bottom); 
    } 
    } 
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谢谢你的例子,这有点矫枉过正,但给了我一个想法如何实现我的目标。 – Alien 2010-08-17 15:02:44

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是的,这里有很多......这只是我碰巧得到的一些资源。如果它真的帮助你,不要忘记点击小号复选标记:) – iandisme 2010-08-17 17:42:47

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嗯,fredley的表面视图提示也很棒,WarrenFaith的教程链接也很好,所以我不能真正地决定谁应该得到复选标记:) – Alien 2010-08-17 18:34:39