d84c652a4e
Bug: 76461699 Bug: 76448408 Test: No change in behavior, no new tests Add class level docs for ImageDecoder, including sample code. Update wording to be more clear and less wordy. Fix broken attempts at using sample code. Incorporate advice at go/android-api-guidelines and https://developers.google.com/style/api-reference-comments Change-Id: Iaf1334993f6cd2d3f6e53d3fb70ef9c7a95c9a76
90 lines
4.2 KiB
Java
90 lines
4.2 KiB
Java
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.graphics;
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import android.annotation.NonNull;
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import android.graphics.drawable.AnimatedImageDrawable;
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import android.graphics.drawable.Drawable;
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/**
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* Helper interface for adding custom processing to an image.
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*
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* <p>The image being processed may be a {@link Drawable}, a {@link Bitmap}, or
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* a frame of an {@link AnimatedImageDrawable} produced by {@link ImageDecoder}.
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* This is called before the requested object is returned.</p>
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*
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* <p>This custom processing can even be applied to images that will be returned
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* as immutable objects, such as a {@link Bitmap} with {@code Config}
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* {@link Bitmap.Config#HARDWARE} returned by {@link ImageDecoder}.</p>
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*
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* <p>On an {@link AnimatedImageDrawable}, the callback will only be called once,
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* but the drawing commands will be applied to each frame, as if the {@link Canvas}
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* had been returned by {@link Picture#beginRecording Picture.beginRecording}.<p>
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*
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* <p>Supplied to ImageDecoder via {@link ImageDecoder#setPostProcessor setPostProcessor}.</p>
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*/
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public interface PostProcessor {
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/**
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* Do any processing after (for example) decoding.
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*
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* <p>Drawing to the {@link Canvas} will behave as if the initial processing
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* (e.g. decoding) already exists in the Canvas. An implementation can draw
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* effects on top of this, or it can even draw behind it using
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* {@link PorterDuff.Mode#DST_OVER PorterDuff.Mode.DST_OVER}. A common
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* effect is to add transparency to the corners to achieve rounded corners.
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* That can be done with the following code:</p>
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*
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* <pre class="prettyprint">
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* Path path = new Path();
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* path.setFillType(Path.FillType.INVERSE_EVEN_ODD);
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* int width = canvas.getWidth();
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* int height = canvas.getHeight();
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* path.addRoundRect(0, 0, width, height, 20, 20, Path.Direction.CW);
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* Paint paint = new Paint();
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* paint.setAntiAlias(true);
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* paint.setColor(Color.TRANSPARENT);
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* paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
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* canvas.drawPath(path, paint);
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* return PixelFormat.TRANSLUCENT;
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* </pre>
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*
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*
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* @param canvas The {@link Canvas} to draw to.
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* @return Opacity of the result after drawing.
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* {@link PixelFormat#UNKNOWN PixelFormat.UNKNOWN} means that the
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* implementation did not change whether the image has alpha. Return
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* this unless you added transparency (e.g. with the code above, in
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* which case you should return
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* {@link PixelFormat#TRANSLUCENT PixelFormat.TRANSLUCENT}) or you
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* forced the image to be opaque (e.g. by drawing everywhere with an
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* opaque color and {@link PorterDuff.Mode#DST_OVER PorterDuff.Mode.DST_OVER},
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* in which case you should return {@link PixelFormat#OPAQUE PixelFormat.OPAQUE}).
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* {@link PixelFormat#TRANSLUCENT PixelFormat.TRANSLUCENT} means that
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* the implementation added transparency. This is safe to return even
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* if the image already had transparency. This is also safe to return
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* if the result is opaque, though it may draw more slowly.
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* {@link PixelFormat#OPAQUE PixelFormat.OPAQUE} means that the
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* implementation forced the image to be opaque. This is safe to return
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* even if the image was already opaque.
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* {@link PixelFormat#TRANSPARENT PixelFormat.TRANSPARENT} (or any other
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* integer) is not allowed, and will result in throwing an
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* {@link java.lang.IllegalArgumentException}.
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*/
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@PixelFormat.Opacity
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public int onPostProcess(@NonNull Canvas canvas);
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}
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