| /* |
| * Copyright (C) 2015 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 com.android.layoutlib.bridge.impl.ResourceHelper; |
| |
| import android.graphics.Canvas; |
| 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; |
| |
| /** |
| * 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 int START_COLOR = ResourceHelper.getColor("#37000000"); |
| private static final int END_COLOR = ResourceHelper.getColor("#03000000"); |
| private static final float PERPENDICULAR_ANGLE = 90f; |
| |
| public static void paintShadow(Outline viewOutline, float elevation, Canvas canvas) { |
| float shadowSize = elevationToShadow(elevation); |
| int saved = modifyCanvas(canvas, shadowSize); |
| if (saved == -1) { |
| 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); |
| Rect outline = viewOutline.mRect; |
| float radius = viewOutline.mRadius; |
| 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); |
| } 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; |
| } |
| |
| /** |
| * 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; |
| } |
| 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. |
| canvas.clipRect(-canvas.getWidth(), -canvas.getHeight(), canvas.getWidth(), |
| canvas.getHeight(), Op.REPLACE); |
| canvas.translate(0, shadowSize / 2f); |
| return saved; |
| } |
| |
| private static void sideShadow(Canvas canvas, Paint edgePaint, |
| RectF edgeShadowRect, float dx, float dy, int rotations) { |
| int saved = canvas.save(); |
| canvas.translate(dx, dy); |
| canvas.rotate(rotations * PERPENDICULAR_ANGLE); |
| canvas.drawRect(edgeShadowRect, edgePaint); |
| canvas.restoreToCount(saved); |
| } |
| |
| /** |
| * @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); |
| } |
| } |