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?
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?
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-series)http://www.droidnova.com/playing-with-graphics-in-android-part-i,147.html
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);
}
}
感谢您阅读本教程,我将阅读它。 – Alien 2010-08-17 15:03:15
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
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