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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 generates a 0 alpha, rectangular Outline the size of the View if a background
* isn't present.
*
* @see Drawable#getOutline(Outline)
*/
public static final ViewOutlineProvider BACKGROUND = new ViewOutlineProvider() {
@Override
public void getOutline(View view, Outline outline) {
Drawable background = view.getBackground();
if (background != null) {
background.getOutline(outline);
} else {
outline.setRect(0, 0, view.getWidth(), view.getHeight());
outline.setAlpha(0.0f);
}
}
};
/**
* Maintains the outline of the View to match its rectangular bounds,
* at <code>1.0f</code> alpha.
*
* This can be used to enable Views that are opaque but lacking a background cast a shadow.
*/
public static final ViewOutlineProvider BOUNDS = new ViewOutlineProvider() {
@Override
public void getOutline(View view, Outline outline) {
outline.setRect(0, 0, view.getWidth(), view.getHeight());
}
};
/**
* Maintains the outline of the View to match its rectangular padded bounds,
* at <code>1.0f</code> alpha.
*
* This can be used to enable Views that are opaque but lacking a background cast a shadow.
*/
public static final ViewOutlineProvider PADDED_BOUNDS = new ViewOutlineProvider() {
@Override
public void getOutline(View view, Outline outline) {
outline.setRect(view.getPaddingLeft(),
view.getPaddingTop(),
view.getWidth() - view.getPaddingRight(),
view.getHeight() - view.getPaddingBottom());
}
};
/**
* 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.
*
* The input outline is empty and has an alpha of <code>1.0f</code>.
*
* @param view The view building the outline.
* @param outline The empty outline to be populated.
*/
public abstract void getOutline(View view, Outline outline);
}
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