Merge "Tweak RenderNode's docs"

This commit is contained in:
TreeHugger Robot
2019-03-13 19:36:21 +00:00
committed by Android (Google) Code Review

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@@ -70,8 +70,7 @@ import java.lang.annotation.RetentionPolicy;
* canvas.drawRect(...);
* } finally {
* renderNode.endRecording();
* }
* </pre>
* }</pre>
*
* <h3>Drawing a RenderNode in a View</h3>
* <pre class="prettyprint">
@@ -84,8 +83,7 @@ import java.lang.annotation.RetentionPolicy;
* // Draw the RenderNode into this canvas.
* canvas.drawRenderNode(myRenderNode);
* }
* }
* </pre>
* }</pre>
*
* <h3>Releasing resources</h3>
* <p>This step is not mandatory but recommended if you want to release resources
@@ -93,8 +91,7 @@ import java.lang.annotation.RetentionPolicy;
* <pre class="prettyprint">
* // Discards the display list content allowing for any held resources to be released.
* // After calling this
* renderNode.discardDisplayList();
* </pre>
* renderNode.discardDisplayList();</pre>
*
*
* <h3>Properties</h3>
@@ -132,8 +129,7 @@ import java.lang.annotation.RetentionPolicy;
* // will be invoked and will execute very quickly
* mRenderNode.offsetLeftAndRight(x);
* invalidate();
* }
* </pre>
* }</pre>
*
* <p>A few of the properties may at first appear redundant, such as {@link #setElevation(float)}
* and {@link #setTranslationZ(float)}. The reason for these duplicates are to allow for a
@@ -146,24 +142,26 @@ import java.lang.annotation.RetentionPolicy;
* overlap with {@link #setPosition(Rect)}.
*
* <p>The RenderNode's transform matrix is computed at render time as follows:
* First a setTranslate(getTranslationX(), getTranslationY()) is applied to a {@link Matrix}.
* Second a preRotate(getRotationZ(), getPivotX(), getPivotY()) is applied to the matrix. And
* finally a preScale(getScaleX(), getScaleY(), getPivotX(), getPivotY()) is applied. The current
* canvas transform matrix, which is translated to the RenderNode's position,
* is then multiplied by the RenderNode's transform matrix. Therefore there is no implicit
* ordering in setting various RenderNode properties. That is to say that:
* <pre class="prettyprint">
* Matrix transform = new Matrix();
* transform.setTranslate(renderNode.getTranslationX(), renderNode.getTranslationY());
* transform.preRotate(renderNode.getRotationZ(),
* renderNode.getPivotX(), renderNode.getPivotY());
* transform.preScale(renderNode.getScaleX(), renderNode.getScaleY(),
* renderNode.getPivotX(), renderNode.getPivotY());</pre>
* The current canvas transform matrix, which is translated to the RenderNode's position,
* is then multiplied by the RenderNode's transform matrix. Therefore the ordering of calling
* property setters does not affect the result. That is to say that:
*
* <pre class="prettyprint">
* renderNode.setTranslationX(100);
* renderNode.setScaleX(100);
* </pre>
* renderNode.setScaleX(100);</pre>
*
* is equivalent to
* is equivalent to:
*
* <pre class="prettyprint">
* renderNode.setScaleX(100);
* renderNode.setTranslationX(100);
* </pre>
* renderNode.setTranslationX(100);</pre>
*
* <h3>Threading</h3>
* <p>RenderNode may be created and used on any thread but they are not thread-safe. Only
@@ -182,8 +180,7 @@ import java.lang.annotation.RetentionPolicy;
* if (needsUpdate) {
* myOwningView.invalidate();
* }
* }
* </pre>
* }</pre>
* This is marginally faster than doing a more explicit up-front check if the value changed by
* comparing the desired value against {@link #getTranslationX()} as it minimizes JNI transitions.
* The actual mechanism of requesting a new frame to be rendered will depend on how this