graphics/java/android/graphics/LinearGradient.java

/*
 * Copyright (C) 2007 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.graphics;

import android.annotation.ColorInt;
import android.annotation.ColorLong;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.compat.annotation.UnsupportedAppUsage;


public class LinearGradient extends Shader {
    @UnsupportedAppUsage
    private float mX0;
    @UnsupportedAppUsage
    private float mY0;
    @UnsupportedAppUsage
    private float mX1;
    @UnsupportedAppUsage
    private float mY1;
    @UnsupportedAppUsage
    private float[] mPositions;
    @UnsupportedAppUsage
    private TileMode mTileMode;

    // @ColorInts are replaced by @ColorLongs, but these remain due to @UnsupportedAppUsage.
    @UnsupportedAppUsage
    @ColorInt
    private int[] mColors;
    @UnsupportedAppUsage
    @ColorInt
    private int mColor0;
    @UnsupportedAppUsage
    @ColorInt
    private int mColor1;

    @ColorLong
    private final long[] mColorLongs;


    /**
     * Create a shader that draws a linear gradient along a line.
     *
     * @param x0           The x-coordinate for the start of the gradient line
     * @param y0           The y-coordinate for the start of the gradient line
     * @param x1           The x-coordinate for the end of the gradient line
     * @param y1           The y-coordinate for the end of the gradient line
     * @param colors       The sRGB colors to be distributed along the gradient line
     * @param positions    May be null. The relative positions [0..1] of
     *                     each corresponding color in the colors array. If this is null,
     *                     the the colors are distributed evenly along the gradient line.
     * @param tile         The Shader tiling mode
     */
    public LinearGradient(float x0, float y0, float x1, float y1, @NonNull @ColorInt int[] colors,
            @Nullable float[] positions, @NonNull TileMode tile) {
        this(x0, y0, x1, y1, convertColors(colors), positions, tile,
                ColorSpace.get(ColorSpace.Named.SRGB));
    }

    /**
     * Create a shader that draws a linear gradient along a line.
     *
     * @param x0           The x-coordinate for the start of the gradient line
     * @param y0           The y-coordinate for the start of the gradient line
     * @param x1           The x-coordinate for the end of the gradient line
     * @param y1           The y-coordinate for the end of the gradient line
     * @param colors       The colors to be distributed along the gradient line
     * @param positions    May be null. The relative positions [0..1] of
     *                     each corresponding color in the colors array. If this is null,
     *                     the the colors are distributed evenly along the gradient line.
     * @param tile         The Shader tiling mode
     *
     * @throws IllegalArgumentException if there are less than two colors, the colors do
     *      not share the same {@link ColorSpace} or do not use a valid one, or {@code positions}
     *      is not {@code null} and has a different length from {@code colors}.
     */
    public LinearGradient(float x0, float y0, float x1, float y1, @NonNull @ColorLong long[] colors,
            @Nullable float[] positions, @NonNull TileMode tile) {
        this(x0, y0, x1, y1, colors.clone(), positions, tile, detectColorSpace(colors));
    }

    /**
     * Base constructor. Assumes @param colors is a copy that this object can hold onto,
     * and all colors share @param colorSpace.
     */
    private LinearGradient(float x0, float y0, float x1, float y1,
            @NonNull @ColorLong long[] colors, @Nullable float[] positions, @NonNull TileMode tile,
            @NonNull ColorSpace colorSpace) {
        super(colorSpace);

        if (positions != null && colors.length != positions.length) {
            throw new IllegalArgumentException("color and position arrays must be of equal length");
        }
        mX0 = x0;
        mY0 = y0;
        mX1 = x1;
        mY1 = y1;
        mColorLongs = colors;
        mPositions = positions != null ? positions.clone() : null;
        mTileMode = tile;
    }

    /**
     * Create a shader that draws a linear gradient along a line.
     *
     * @param x0       The x-coordinate for the start of the gradient line
     * @param y0       The y-coordinate for the start of the gradient line
     * @param x1       The x-coordinate for the end of the gradient line
     * @param y1       The y-coordinate for the end of the gradient line
     * @param color0   The sRGB color at the start of the gradient line.
     * @param color1   The sRGB color at the end of the gradient line.
     * @param tile     The Shader tiling mode
     */
    public LinearGradient(float x0, float y0, float x1, float y1,
            @ColorInt int color0, @ColorInt int color1,
            @NonNull TileMode tile) {
        this(x0, y0, x1, y1, Color.pack(color0), Color.pack(color1), tile);
    }

    /**
     * Create a shader that draws a linear gradient along a line.
     *
     * @param x0       The x-coordinate for the start of the gradient line
     * @param y0       The y-coordinate for the start of the gradient line
     * @param x1       The x-coordinate for the end of the gradient line
     * @param y1       The y-coordinate for the end of the gradient line
     * @param color0   The color at the start of the gradient line.
     * @param color1   The color at the end of the gradient line.
     * @param tile     The Shader tiling mode
     *
     * @throws IllegalArgumentException if the colors do
     *      not share the same {@link ColorSpace} or do not use a valid one.
     */
    public LinearGradient(float x0, float y0, float x1, float y1,
            @ColorLong long color0, @ColorLong long color1,
            @NonNull TileMode tile) {
        this(x0, y0, x1, y1, new long[] {color0, color1}, null, tile);
    }

    /** @hide */
    @Override
    protected long createNativeInstance(long nativeMatrix) {
        return nativeCreate(nativeMatrix, mX0, mY0, mX1, mY1,
                mColorLongs, mPositions, mTileMode.nativeInt,
                colorSpace().getNativeInstance());
    }

    private native long nativeCreate(long matrix, float x0, float y0, float x1, float y1,
            long[] colors, float[] positions, int tileMode, long colorSpaceHandle);
}