blocks|key|1279152|text|我不完全清楚您要做的是什么，但我相信BitmapDrawable和LayerDrawable的组合可能会起作用。BitmapDrawable允许您将位图用作可绘制图形，然后您可以使用LayerDrawable将蒙版分层到另一个可绘制图形之上。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1279153|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/intl/fr/reference/android/graphics/drawable/BitmapDrawable.html|1|http://developer.android.com/intl/fr/reference/android/graphics/drawable/LayerDrawable.html^0|I|E|X|D|I|E|0|X|D|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]|$9|S|A|T|B|C]]|D|@$9|U|A|V|1|W]|$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]|N|$5|I|J|K|E|$L|O]]]]

I'm not entirely clear on what you're going for, but I believe that a combination of <a href="http://developer.android.com/intl/fr/reference/android/graphics/drawable/BitmapDrawable.html" rel="nofollow noreferrer"><code>BitmapDrawable</code></a> and <a href="http://developer.android.com/intl/fr/reference/android/graphics/drawable/LayerDrawable.html" rel="nofollow noreferrer"><code>LayerDrawable</code></a> may work. BitmapDrawable will allow you to use your Bitmaps as Drawables, and then you can use LayerDrawable to layer the mask on top of another Drawable.

blocks|key|1064521|text|使用API+Demo中的Xfermodes示例，我能够使用应用于Paint对象的PorterDuffXfermode将画布上的两个位图混合在一起。这就是我所需要的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1064522|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Using the Xfermodes example in the API Demo I was able to use a PorterDuffXfermode applied to a Paint object to blend together two bitmaps on a canvas. This works exactly how I need it to.

blocks|key|1064563|text|我让它工作了，所以它是这样的|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1064564|++++//+we+first+same+the+layer,+rectF+is+the+area+of+interest+we+plan+on+drawing
++++//+this+will+create+an+offscreen+bitmap
++++canvas.saveLayer(rectF,+null,+Canvas.MATRIX_SAVE_FLAG
++++++++++++%7C+Canvas.CLIP_SAVE_FLAG+%7C+Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
++++++++++++%7C+Canvas.FULL_COLOR_LAYER_SAVE_FLAG
++++++++++++%7C+Canvas.CLIP_TO_LAYER_SAVE_FLAG);

++++//+draw+our+unmasked+stuff
++++super.draw(canvas);
++++//+We+same+a+layer+again+but+this+time+we+pass+a+paint+object+to+mask
++++//+the+above+layer
++++maskPaint+=+new+Paint()
++++maskPaint.setColor(0xFFFFFFFF);
++++maskPaint.setXfermode(new+PorterDuffXfermode(PorterDuff.Mode.MULTIPLY));

++++canvas.saveLayer(rectF,+maskPaint,
++++++++++++Canvas.MATRIX_SAVE_FLAG+%7C+Canvas.CLIP_SAVE_FLAG
++++++++++++++++++++%7C+Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
++++++++++++++++++++%7C+Canvas.FULL_COLOR_LAYER_SAVE_FLAG
++++++++++++++++++++%7C+Canvas.CLIP_TO_LAYER_SAVE_FLAG);
++++//+we+draw+the+mask+which+is+black+and+white.+In+my+case
++++//+I+have+a+path,+and+I+use+a+blurPaint+which+blurs+the+mask+slightly
++++//+You+can+do+anti+aliasing+or+whatever+you+which.+Just+black+&+white
++++canvas.drawPath(path,+blurPaint);
++++//+We+restore+twice,+this+merges+the+results+upward
++++//+as+each+saveLayer()+allocates+a+new+drawing+bitmap
++++canvas.restore();
++++canvas.restore();|code-block|syntax|javascript|1064565|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I got it working, so it's something like this

<pre><code> // we first same the layer, rectF is the area of interest we plan on drawing
 // this will create an offscreen bitmap
 canvas.saveLayer(rectF, null, Canvas.MATRIX_SAVE_FLAG
 | Canvas.CLIP_SAVE_FLAG | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
 | Canvas.FULL_COLOR_LAYER_SAVE_FLAG
 | Canvas.CLIP_TO_LAYER_SAVE_FLAG);

 // draw our unmasked stuff
 super.draw(canvas);
 // We same a layer again but this time we pass a paint object to mask
 // the above layer
 maskPaint = new Paint()
 maskPaint.setColor(0xFFFFFFFF);
 maskPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY));

 canvas.saveLayer(rectF, maskPaint,
 Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG
 | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
 | Canvas.FULL_COLOR_LAYER_SAVE_FLAG
 | Canvas.CLIP_TO_LAYER_SAVE_FLAG);
 // we draw the mask which is black and white. In my case
 // I have a path, and I use a blurPaint which blurs the mask slightly
 // You can do anti aliasing or whatever you which. Just black &amp; white
 canvas.drawPath(path, blurPaint);
 // We restore twice, this merges the results upward
 // as each saveLayer() allocates a new drawing bitmap
 canvas.restore();
 canvas.restore();
</code></pre>

blocks|key|1279315|text|我做了一个可屏蔽的布局。这是一个框架布局，您可以在其中指定xporterduffmode和掩码。你可以在这里找到它：https://github.com/christophesmet/android_maskable_layout|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1279316|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/christophesmet/android_maskable_layout^0|1M|1L|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

I made a maskable layout.
It's a framelayout where you can specifiy the xporterduffmode and the mask.
You can find it here: <a href="https://github.com/christophesmet/android_maskable_layout" rel="nofollow">https://github.com/christophesmet/android_maskable_layout</a>

blocks|key|1064682|text|我的解决方案与@over_optimistic的解决方案非常接近，只需少一次saveLayer()调用。我使用可抽出的遮罩而不是路径，在我的例子中它是一张光盘。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1064683|我将这些变量声明为字段(最好在onDraw方法之外分配内存)：|1064684|private+Paint+maskingPaint+=+new+Paint();
private+Drawable+mask+=+<insert+your+drawable+here>|code-block|syntax|javascript|1064685|然后，在onDraw()之外的某个地方设置对象：|1064686|//+Xfermode+won't+work+if+hardware+accelerated
setLayerType(View.LAYER_TYPE_SOFTWARE,+null);

//+Using+destination+shape+as+a+mask
//+For+a+good+explanation+of+PorterDuff+transfer+modes+:+http://ssp.impulsetrain.com/porterduff.html
maskingPaint.setXfermode(new+PorterDuffXfermode(Mode.SRC_IN));
maskingPaint.setAntiAlias(true);

//+Position+the+mask
mask.setBounds(<insert+your+mask+bounds+here>);|1064687|最后，onDraw()方法应用掩码：|1064688|@Override
protected+synchronized+void+onDraw(Canvas+canvas)
{
++++//+Draw+the+mask+first,+making+it+the+PorterDuff+destination
++++mask.draw(canvas);

++++//+Save+the+layer+with+the+masking+paint,+that+will+be+applied+on+restore()
++++//+Using+CLIP_TO_LAYER_SAVE_FLAG+to+avoid+any+overflow+of+the+masked+image+outside+the+mask+bounds.
++++Rect+bounds+=+mask.getBounds();
++++canvas.saveLayer(bounds.left,+bounds.top,+bounds.right,+bounds.bottom,+maskingPaint,+
++++++++++++Canvas.CLIP_TO_LAYER_SAVE_FLAG);

++++//+Draw+the+shape+offscreen,+making+it+the+PorterDuff+source
++++super.onDraw(canvas);

++++//+Apply+the+source+to+the+destination,+using+SRC_IN+transfer+mode
++++canvas.restore();
}|1064689|为了更好地理解传输模式，我参考了http://ssp.impulsetrain.com/porterduff.html。这个页面读起来很有趣。在那之后，用同样的代码，你将能够获得比简单的掩码更多的东西！|offset|length|1064690|entityMap|0|LINK|mutability|MUTABLE|url|http://ssp.impulsetrain.com/porterduff.html^0|0|0|0|0|0|0|0|G|17|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|15|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|16|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|17|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|18|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|19|8|@]|9|@$S|1A|T|1B|1|1C]]|A|$]]|$1|U|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]]]

My solution is close to @over_optimistic's solution, less one saveLayer() call. I use a Drawable mask instead of a path, in my case it was a disc.

I declared these variables as fields (it's good practice to allocate memory outside of onDraw method):

<pre><code>private Paint maskingPaint = new Paint();
private Drawable mask = &lt;insert your drawable here&gt;
</code></pre>

Then, somewhere outside of onDraw(), setup the objects:

<pre><code>// Xfermode won't work if hardware accelerated
setLayerType(View.LAYER_TYPE_SOFTWARE, null);

// Using destination shape as a mask
// For a good explanation of PorterDuff transfer modes : http://ssp.impulsetrain.com/porterduff.html
maskingPaint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
maskingPaint.setAntiAlias(true);

// Position the mask
mask.setBounds(&lt;insert your mask bounds here&gt;);
</code></pre>

Then finally, the onDraw() method applies the mask:

<pre><code>@Override
protected synchronized void onDraw(Canvas canvas)
{
 // Draw the mask first, making it the PorterDuff destination
 mask.draw(canvas);

 // Save the layer with the masking paint, that will be applied on restore()
 // Using CLIP_TO_LAYER_SAVE_FLAG to avoid any overflow of the masked image outside the mask bounds.
 Rect bounds = mask.getBounds();
 canvas.saveLayer(bounds.left, bounds.top, bounds.right, bounds.bottom, maskingPaint, 
 Canvas.CLIP_TO_LAYER_SAVE_FLAG);

 // Draw the shape offscreen, making it the PorterDuff source
 super.onDraw(canvas);

 // Apply the source to the destination, using SRC_IN transfer mode
 canvas.restore();
}
</code></pre>

For a better understanding of the transfer modes, I referred to <a href="http://ssp.impulsetrain.com/porterduff.html" rel="noreferrer">http://ssp.impulsetrain.com/porterduff.html</a>.
That page is pretty interesting to read. After that, with the same kind of code you'll be able to acheive much more than a simple mask!

I'm currently looking for a way to use a black and white bitmap to mask the alpha channel of another bitmap or Drawable on Android. I'm curious as to what the best way to do this is. I certainly have a couple of ideas for how to do this, but they are not optimal.

I need to be able to apply a new mask to the image every so often (the black and white bitmap will change every few seconds).

Any feedback on how to achieve this would be greatly appreciated.

Masking a Drawable/Bitmap on Android

Android

我目前正在寻找一种方法来使用黑白位图来遮罩另一个位图或可在Android上绘制的alpha通道。我很好奇做这件事最好的方法是什么。我当然有几个关于如何做到这一点的想法，但它们并不是最佳的。我需要能够将新的蒙版应用到图像中(黑白位图每隔几秒钟就会改变一次)。任何关于如何实现这一点的反馈都将非常感谢。

问在Android上屏蔽可绘制/位图
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问在Android上屏蔽可绘制/位图EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问在Android上屏蔽可绘制/位图
EN