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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.view;
import android.graphics.Outline;
import android.graphics.drawable.Drawable;
/**
* Interface by which a View builds its {@link Outline}, used for shadow casting and clipping.
*/
public abstract class ViewOutlineProvider {
/**
* Default outline provider for Views, which queries the Outline from the View's background,
* or returns <code>false</code> if the View does not have a background.
*
* @see Drawable#getOutline(Outline)
*/
public static final ViewOutlineProvider BACKGROUND = new ViewOutlineProvider() {
@Override
public boolean getOutline(View view, Outline outline) {
Drawable background = view.getBackground();
if (background == null) {
// no background, no outline
return false;
}
return background.getOutline(outline);
}
};
/**
* Called to get the provider to populate the Outline.
*
* This method will be called by a View when its owned Drawables are invalidated, when the
* View's size changes, or if {@link View#invalidateOutline()} is called
* explicitly.
*
* @param view The view building the outline.
* @param outline The empty outline to be populated.
* @return true if this View should have an outline, else false. The outline must be
* populated by this method, and non-empty if true is returned.
*/
public abstract boolean getOutline(View view, Outline outline);
}
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