114 lines
3.9 KiB
Java
114 lines
3.9 KiB
Java
/*
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* Copyright (C) 2017 Jared Rummler
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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 com.jaredrummler.android.colorpicker;
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import android.graphics.Bitmap;
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import android.graphics.Bitmap.Config;
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import android.graphics.Canvas;
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import android.graphics.ColorFilter;
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import android.graphics.Paint;
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import android.graphics.Rect;
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import android.graphics.drawable.Drawable;
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/**
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* This drawable will draw a simple white and gray chessboard pattern.
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* It's the pattern you will often see as a background behind a partly transparent image in many applications.
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*/
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class AlphaPatternDrawable extends Drawable {
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private final Paint paint = new Paint();
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private final Paint paintWhite = new Paint();
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private final Paint paintGray = new Paint();
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private int rectangleSize = 10;
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private int numRectanglesHorizontal;
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private int numRectanglesVertical;
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/**
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* Bitmap in which the pattern will be cached.
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* This is so the pattern will not have to be recreated each time draw() gets called.
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* Because recreating the pattern i rather expensive. I will only be recreated if the size changes.
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*/
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private Bitmap bitmap;
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AlphaPatternDrawable(int rectangleSize) {
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this.rectangleSize = rectangleSize;
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paintWhite.setColor(0xFFFFFFFF);
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paintGray.setColor(0xFFCBCBCB);
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}
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@Override
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public void draw(Canvas canvas) {
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if (bitmap != null && !bitmap.isRecycled()) {
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canvas.drawBitmap(bitmap, null, getBounds(), paint);
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}
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}
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@Override
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public int getOpacity() {
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return 0;
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}
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@Override
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public void setAlpha(int alpha) {
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throw new UnsupportedOperationException("Alpha is not supported by this drawable.");
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}
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@Override
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public void setColorFilter(ColorFilter cf) {
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throw new UnsupportedOperationException("ColorFilter is not supported by this drawable.");
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}
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@Override
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protected void onBoundsChange(Rect bounds) {
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super.onBoundsChange(bounds);
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int height = bounds.height();
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int width = bounds.width();
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numRectanglesHorizontal = (int) Math.ceil((width / rectangleSize));
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numRectanglesVertical = (int) Math.ceil(height / rectangleSize);
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generatePatternBitmap();
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}
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/**
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* This will generate a bitmap with the pattern as big as the rectangle we were allow to draw on.
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* We do this to chache the bitmap so we don't need to recreate it each time draw() is called since it takes a few
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* milliseconds
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*/
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private void generatePatternBitmap() {
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if (getBounds().width() <= 0 || getBounds().height() <= 0) {
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return;
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}
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bitmap = Bitmap.createBitmap(getBounds().width(), getBounds().height(), Config.ARGB_8888);
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Canvas canvas = new Canvas(bitmap);
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Rect r = new Rect();
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boolean verticalStartWhite = true;
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for (int i = 0; i <= numRectanglesVertical; i++) {
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boolean isWhite = verticalStartWhite;
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for (int j = 0; j <= numRectanglesHorizontal; j++) {
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r.top = i * rectangleSize;
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r.left = j * rectangleSize;
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r.bottom = r.top + rectangleSize;
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r.right = r.left + rectangleSize;
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canvas.drawRect(r, isWhite ? paintWhite : paintGray);
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isWhite = !isWhite;
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}
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verticalStartWhite = !verticalStartWhite;
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}
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}
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}
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