Replace rectangle shadow algorithm

/*

 * Copyright (C) 2015 The Android Open Source Project

 * Copyright (C) 2015, 2017 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.

package android.view;

import com.android.layoutlib.bridge.impl.GcSnapshot;

import com.android.layoutlib.bridge.impl.ResourceHelper;

import android.annotation.NonNull;

import android.graphics.Canvas;

import android.graphics.Canvas_Delegate;

import android.graphics.LinearGradient;

import android.graphics.Outline;

import android.graphics.Paint;

import android.graphics.Paint.Style;

import android.graphics.Path;

import android.graphics.Path.FillType;

import android.graphics.RadialGradient;

import android.graphics.Rect;

import android.graphics.RectF;

import android.graphics.Region.Op;

import android.graphics.Shader.TileMode;

import java.awt.Rectangle;

import com.android.layoutlib.bridge.shadowutil.SpotShadow;

import com.android.layoutlib.bridge.shadowutil.ShadowBuffer;

/**

 * Paints shadow for rounded rectangles. Inspiration from CardView. Couldn't use that directly,

 * since it modifies the size of the content, that we can't do.

 */

public class RectShadowPainter {

    private static final float SHADOW_STRENGTH = 0.1f;

    private static final int LIGHT_POINTS = 8;

    private static final int START_COLOR = ResourceHelper.getColor("#37000000");

    private static final int END_COLOR = ResourceHelper.getColor("#03000000");

    private static final float PERPENDICULAR_ANGLE = 90f;

    private static final int QUADRANT_DIVIDED_COUNT = 8;

    public static void paintShadow(Outline viewOutline, float elevation, Canvas canvas) {

    private static final int RAY_TRACING_RAYS = 180;

    private static final int RAY_TRACING_LAYERS = 10;

    public static void paintShadow(@NonNull Outline viewOutline, float elevation,

            @NonNull Canvas canvas) {

        Rect outline = new Rect();

        if (!viewOutline.getRect(outline)) {

            throw new IllegalArgumentException("Outline is not a rect shadow");

        }

        // TODO replacing the algorithm here to create better shadow

        float shadowSize = elevationToShadow(elevation);

        int saved = modifyCanvas(canvas, shadowSize);

        Rect originCanvasRect = canvas.getClipBounds();

        int saved = modifyCanvas(canvas);

        if (saved == -1) {

            return;

        }

        try {

            float radius = viewOutline.getRadius();

            if (radius <= 0) {

                // We can not paint a shadow with radius 0

                return;

            }

        try {

            Paint cornerPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG);

            cornerPaint.setStyle(Style.FILL);

            Paint edgePaint = new Paint(cornerPaint);

            edgePaint.setAntiAlias(false);

            float outerArcRadius = radius + shadowSize;

            int[] colors = {START_COLOR, START_COLOR, END_COLOR};

            cornerPaint.setShader(new RadialGradient(0, 0, outerArcRadius, colors,

                    new float[]{0f, radius / outerArcRadius, 1f}, TileMode.CLAMP));

            edgePaint.setShader(new LinearGradient(0, 0, -shadowSize, 0, START_COLOR, END_COLOR,

                    TileMode.CLAMP));

            Path path = new Path();

            path.setFillType(FillType.EVEN_ODD);

            // A rectangle bounding the complete shadow.

            RectF shadowRect = new RectF(outline);

            shadowRect.inset(-shadowSize, -shadowSize);

            // A rectangle with edges corresponding to the straight edges of the outline.

            RectF inset = new RectF(outline);

            inset.inset(radius, radius);

            // A rectangle used to represent the edge shadow.

            RectF edgeShadowRect = new RectF();

            // left and right sides.

            edgeShadowRect.set(-shadowSize, 0f, 0f, inset.height());

            // Left shadow

            sideShadow(canvas, edgePaint, edgeShadowRect, outline.left, inset.top, 0);

            // Right shadow

            sideShadow(canvas, edgePaint, edgeShadowRect, outline.right, inset.bottom, 2);

            // Top shadow

            edgeShadowRect.set(-shadowSize, 0, 0, inset.width());

            sideShadow(canvas, edgePaint, edgeShadowRect, inset.right, outline.top, 1);

            // bottom shadow. This needs an inset so that blank doesn't appear when the content is

            // moved up.

            edgeShadowRect.set(-shadowSize, 0, shadowSize / 2f, inset.width());

            edgePaint.setShader(new LinearGradient(edgeShadowRect.right, 0, edgeShadowRect.left, 0,

                    colors, new float[]{0f, 1 / 3f, 1f}, TileMode.CLAMP));

            sideShadow(canvas, edgePaint, edgeShadowRect, inset.left, outline.bottom, 3);

            // Draw corners.

            drawCorner(canvas, cornerPaint, path, inset.right, inset.bottom, outerArcRadius, 0);

            drawCorner(canvas, cornerPaint, path, inset.left, inset.bottom, outerArcRadius, 1);

            drawCorner(canvas, cornerPaint, path, inset.left, inset.top, outerArcRadius, 2);

            drawCorner(canvas, cornerPaint, path, inset.right, inset.top, outerArcRadius, 3);

            // view's absolute position in this canvas.

            int viewLeft = -originCanvasRect.left + outline.left;

            int viewTop = -originCanvasRect.top + outline.top;

            int viewRight = viewLeft + outline.width();

            int viewBottom = viewTop + outline.height();

            float[][] rectangleCoordinators = generateRectangleCoordinates(viewLeft, viewTop,

                    viewRight, viewBottom, radius, elevation);

            // TODO: get these values from resources.

            float lightPosX = canvas.getWidth() / 2;

            float lightPosY = 0;

            float lightHeight = 1800;

            float lightSize = 200;

            paintGeometricShadow(rectangleCoordinators, lightPosX, lightPosY, lightHeight,

                    lightSize, canvas);

        } finally {

            canvas.restoreToCount(saved);

        }

    }

    private static float elevationToShadow(float elevation) {

        // The factor is chosen by eyeballing the shadow size on device and preview.

        return elevation * 0.5f;

    private static int modifyCanvas(@NonNull Canvas canvas) {

        Rect rect = canvas.getClipBounds();

        canvas.translate(rect.left, rect.top);

        return canvas.save();

    }

    /**

     * Translate canvas by half of shadow size up, so that it appears that light is coming

     * slightly from above. Also, remove clipping, so that shadow is not clipped.

     */

    private static int modifyCanvas(Canvas canvas, float shadowSize) {

        Rect clipBounds = canvas.getClipBounds();

        if (clipBounds.isEmpty()) {

            return -1;

    @NonNull

    private static float[][] generateRectangleCoordinates(float left, float top, float right,

            float bottom, float radius, float elevation) {

        left = left + radius;

        top = top + radius;

        right = right - radius;

        bottom = bottom - radius;

        final double RADIANS_STEP = 2 * Math.PI / 4 / QUADRANT_DIVIDED_COUNT;

        float[][] ret = new float[QUADRANT_DIVIDED_COUNT * 4][3];

        int points = 0;

        // left-bottom points

        for (int i = 0; i < QUADRANT_DIVIDED_COUNT; i++) {

            ret[points][0] = (float) (left - radius + radius * Math.cos(RADIANS_STEP * i));

            ret[points][1] = (float) (bottom + radius - radius * Math.cos(RADIANS_STEP * i));

            ret[points][2] = elevation;

            points++;

        }

        int saved = canvas.save();

        // Usually canvas has been translated to the top left corner of the view when this is

        // called. So, setting a clip rect at 0,0 will clip the top left part of the shadow.

        // Thus, we just expand in each direction by width and height of the canvas, while staying

        // inside the original drawing region.

        GcSnapshot snapshot = Canvas_Delegate.getDelegate(canvas).getSnapshot();

        Rectangle originalClip = snapshot.getOriginalClip();

        if (originalClip != null) {

            canvas.clipRect(originalClip.x, originalClip.y, originalClip.x + originalClip.width,

              originalClip.y + originalClip.height, Op.REPLACE);

            canvas.clipRect(-canvas.getWidth(), -canvas.getHeight(), canvas.getWidth(),

              canvas.getHeight(), Op.INTERSECT);

        // left-top points

        for (int i = 0; i < QUADRANT_DIVIDED_COUNT; i++) {

            ret[points][0] = (float) (left + radius - radius * Math.cos(RADIANS_STEP * i));

            ret[points][1] = (float) (top + radius - radius * Math.cos(RADIANS_STEP * i));

            ret[points][2] = elevation;

            points++;

        }

        canvas.translate(0, shadowSize / 2f);

        return saved;

        // right-top points

        for (int i = 0; i < QUADRANT_DIVIDED_COUNT; i++) {

            ret[points][0] = (float) (right + radius - radius * Math.cos(RADIANS_STEP * i));

            ret[points][1] = (float) (top + radius + radius * Math.cos(RADIANS_STEP * i));

            ret[points][2] = elevation;

            points++;

        }

        // right-bottom point

        for (int i = 0; i < QUADRANT_DIVIDED_COUNT; i++) {

            ret[points][0] = (float) (right - radius + radius * Math.cos(RADIANS_STEP * i));

            ret[points][1] = (float) (bottom - radius + radius * Math.cos(RADIANS_STEP * i));

            ret[points][2] = elevation;

            points++;

        }

    private static void sideShadow(Canvas canvas, Paint edgePaint,

            RectF edgeShadowRect, float dx, float dy, int rotations) {

        if (isRectEmpty(edgeShadowRect)) {

            return;

        return ret;

    }

        int saved = canvas.save();

        canvas.translate(dx, dy);

        canvas.rotate(rotations * PERPENDICULAR_ANGLE);

        canvas.drawRect(edgeShadowRect, edgePaint);

        canvas.restoreToCount(saved);

    private static void paintGeometricShadow(@NonNull float[][] coordinates, float lightPosX,

            float lightPosY, float lightHeight, float lightSize, Canvas canvas) {

        // The polygon of shadow (same as the original item)

        float[] shadowPoly = new float[coordinates.length * 3];

        for (int i = 0; i < coordinates.length; i++) {

            shadowPoly[i * 3 + 0] = coordinates[i][0];

            shadowPoly[i * 3 + 1] = coordinates[i][1];

            shadowPoly[i * 3 + 2] = coordinates[i][2];

        }

    /**

     * @param canvas Canvas to draw the rectangle on.

     * @param paint Paint to use when drawing the corner.

     * @param path A path to reuse. Prevents allocating memory for each path.

     * @param x Center of circle, which this corner is a part of.

     * @param y Center of circle, which this corner is a part of.

     * @param radius radius of the arc

     * @param rotations number of quarter rotations before starting to paint the arc.

     */

    private static void drawCorner(Canvas canvas, Paint paint, Path path, float x, float y,

            float radius, int rotations) {

        int saved = canvas.save();

        canvas.translate(x, y);

        path.reset();

        path.arcTo(-radius, -radius, radius, radius, rotations * PERPENDICULAR_ANGLE,

                PERPENDICULAR_ANGLE, false);

        path.lineTo(0, 0);

        path.close();

        canvas.drawPath(path, paint);

        canvas.restoreToCount(saved);

        // TODO: calculate the ambient shadow and mix with Spot shadow.

        // Calculate the shadow of SpotLight

        float[] light = SpotShadow.calculateLight(lightSize, LIGHT_POINTS, lightPosX,

                lightPosY, lightHeight);

        int stripSize = 3 * SpotShadow.getStripSize(RAY_TRACING_RAYS, RAY_TRACING_LAYERS);

        if (stripSize < 9) {

            return;

        }

        float[] strip = new float[stripSize];

        SpotShadow.calcShadow(light, LIGHT_POINTS, shadowPoly, coordinates.length, RAY_TRACING_RAYS,

                RAY_TRACING_LAYERS, 1f, strip);

    /**

     * Differs from {@link RectF#isEmpty()} as this first converts the rect to int and then checks.

     * <p/>

     * This is required because {@link Canvas_Delegate#native_drawRect(long, float, float, float,

     * float, long)} casts the co-ordinates to int and we want to ensure that it doesn't end up

     * drawing empty rectangles, which results in IllegalArgumentException.

     */

    private static boolean isRectEmpty(RectF rect) {

        return (int) rect.left >= (int) rect.right || (int) rect.top >= (int) rect.bottom;

        ShadowBuffer buff = new ShadowBuffer(canvas.getWidth(), canvas.getHeight());

        buff.generateTriangles(strip, SHADOW_STRENGTH);

        buff.draw(canvas);

    }

}

/*

 * Copyright (C) 2017 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 com.android.layoutlib.bridge.shadowutil;

import android.annotation.NonNull;

import android.graphics.Bitmap;

import android.graphics.Bitmap.Config;

import android.graphics.Canvas;

public class ShadowBuffer {

    private int mWidth;

    private int mHeight;

    private Bitmap mBitmap;

    private int[] mData;

    public ShadowBuffer(int width, int height) {

        mWidth = width;

        mHeight = height;

        mBitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);

        mData = new int[mBitmap.getWidth() * mBitmap.getHeight()];

        mBitmap.getPixels(mData, 0, mBitmap.getWidth(), 0, 0, mBitmap.getWidth(),

                mBitmap.getHeight());

    }

    public void generateTriangles(@NonNull float[] strip, float scale) {

        for (int i = 0; i < strip.length - 8; i += 3) {

            float fx3 = strip[i];

            float fy3 = strip[i + 1];

            float fz3 = scale * strip[i + 2];

            float fx2 = strip[i + 3];

            float fy2 = strip[i + 4];

            float fz2 = scale * strip[i + 5];

            float fx1 = strip[i + 6];

            float fy1 = strip[i + 7];

            float fz1 = scale * strip[i + 8];

            if (fx1 * (fy2 - fy3) + fx2 * (fy3 - fy1) + fx3 * (fy1 - fy2) == 0) {

                continue;

            }

            triangleZBuffMin(mData, mWidth, mHeight, fx3, fy3, fz3, fx2, fy2, fz2, fx1, fy1, fz1);

            triangleZBuffMin(mData, mWidth, mHeight, fx1, fy1, fz1, fx2, fy2, fz2, fx3, fy3, fz3);

        }

        mBitmap.setPixels(mData, 0, mBitmap.getWidth(), 0, 0, mBitmap.getWidth(),

                mBitmap.getHeight());

    }

    private void triangleZBuffMin(@NonNull int[] buff, int w, int h, float fx3, float fy3,

            float fz3, float fx2, float fy2, float fz2, float fx1, float fy1, float fz1) {

        if (((fx1 - fx2) * (fy3 - fy2) - (fy1 - fy2) * (fx3 - fx2)) < 0) {

            float tmpX = fx1;

            float tmpY = fy1;

            float tmpZ = fz1;

            fx1 = fx2;

            fy1 = fy2;

            fz1 = fz2;

            fx2 = tmpX;

            fy2 = tmpY;

            fz2 = tmpZ;

        }

        double d = (fx1 * (fy3 - fy2) - fx2 * fy3 + fx3 * fy2 + (fx2 - fx3) * fy1);

        if (d == 0) {

            return;

        }

        float dx = (float) (-(fy1 * (fz3 - fz2) - fy2 * fz3 + fy3 * fz2 + (fy2 - fy3) * fz1) / d);

        float dy = (float) ((fx1 * (fz3 - fz2) - fx2 * fz3 + fx3 * fz2 + (fx2 - fx3) * fz1) / d);

        float zOff = (float) ((fx1 * (fy3 * fz2 - fy2 * fz3) + fy1 * (fx2 * fz3 - fx3 * fz2) +

                (fx3 * fy2 - fx2 * fy3) * fz1) / d);

        int Y1 = (int) (16.0f * fy1 + .5f);

        int Y2 = (int) (16.0f * fy2 + .5f);

        int Y3 = (int) (16.0f * fy3 + .5f);

        int X1 = (int) (16.0f * fx1 + .5f);

        int X2 = (int) (16.0f * fx2 + .5f);

        int X3 = (int) (16.0f * fx3 + .5f);

        int DX12 = X1 - X2;

        int DX23 = X2 - X3;

        int DX31 = X3 - X1;

        int DY12 = Y1 - Y2;

        int DY23 = Y2 - Y3;

        int DY31 = Y3 - Y1;

        int FDX12 = DX12 << 4;

        int FDX23 = DX23 << 4;

        int FDX31 = DX31 << 4;

        int FDY12 = DY12 << 4;

        int FDY23 = DY23 << 4;

        int FDY31 = DY31 << 4;

        int minX = (min(X1, X2, X3) + 0xF) >> 4;

        int maxX = (max(X1, X2, X3) + 0xF) >> 4;

        int minY = (min(Y1, Y2, Y3) + 0xF) >> 4;

        int maxY = (max(Y1, Y2, Y3) + 0xF) >> 4;

        if (minY < 0) {

            minY = 0;

        }

        if (minX < 0) {

            minX = 0;

        }

        if (maxX > w) {

            maxX = w;

        }

        if (maxY > h) {

            maxY = h;

        }

        int off = minY * w;

        int C1 = DY12 * X1 - DX12 * Y1;

        int C2 = DY23 * X2 - DX23 * Y2;

        int C3 = DY31 * X3 - DX31 * Y3;

        if (DY12 < 0 || (DY12 == 0 && DX12 > 0)) {

            C1++;

        }

        if (DY23 < 0 || (DY23 == 0 && DX23 > 0)) {

            C2++;

        }

        if (DY31 < 0 || (DY31 == 0 && DX31 > 0)) {

            C3++;

        }

        int CY1 = C1 + DX12 * (minY << 4) - DY12 * (minX << 4);

        int CY2 = C2 + DX23 * (minY << 4) - DY23 * (minX << 4);

        int CY3 = C3 + DX31 * (minY << 4) - DY31 * (minX << 4);

        for (int y = minY; y < maxY; y++) {

            int CX1 = CY1;

            int CX2 = CY2;

            int CX3 = CY3;

            float p = zOff + dy * y;

            for (int x = minX; x < maxX; x++) {

                if (CX1 > 0 && CX2 > 0 && CX3 > 0) {

                    int point = x + off;

                    float zVal = p + dx * x;

                    buff[point] |= ((int) (zVal * 255)) << 24;

                }

                CX1 -= FDY12;

                CX2 -= FDY23;

                CX3 -= FDY31;

            }

            CY1 += FDX12;

            CY2 += FDX23;

            CY3 += FDX31;

            off += w;

        }

    }

    private int min(int x1, int x2, int x3) {

        return (x1 > x2) ? ((x2 > x3) ? x3 : x2) : ((x1 > x3) ? x3 : x1);

    }

    private int max(int x1, int x2, int x3) {

        return (x1 < x2) ? ((x2 < x3) ? x3 : x2) : ((x1 < x3) ? x3 : x1);

    }

    public void draw(@NonNull Canvas c) {

        c.drawBitmap(mBitmap, 0, 0, null);

    }

}

            android:layout_height="40dp"

            android:layout_alignParentRight="true"

            android:layout_centerVertical="true"

            android:elevation="100dp"

            android:elevation="108dp"

            android:stateListAnimator="@null"/>

    </RelativeLayout>

            android:layout_height="40dp"

            android:layout_alignParentRight="true"

            android:layout_centerVertical="true"

            android:elevation="36dp"

            android:elevation="108dp"

            android:stateListAnimator="@null"/>

    </RelativeLayout>