Java tutorial
//package com.java2s; /* * Copyright (C) 2013 Chen Hui <calmer91@gmail.com> * * 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. */ import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.PorterDuff; import android.graphics.RectF; public class Main { public static Paint PAINT, PAINT_FPS; public static RectF RECT; private static boolean USE_DRAWCOLOR_TO_CLEAR_CANVAS = true; private static boolean USE_DRAWCOLOR_MODE_CLEAR = true; public static void clearCanvas(Canvas canvas) { if (USE_DRAWCOLOR_TO_CLEAR_CANVAS) { if (USE_DRAWCOLOR_MODE_CLEAR) { canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR); } else { canvas.drawColor(Color.TRANSPARENT); } } else { RECT.set(0, 0, canvas.getWidth(), canvas.getHeight()); clearCanvas(canvas, RECT); } } public static void clearCanvas(Canvas canvas, float left, float top, float right, float bottom) { RECT.set(left, top, right, bottom); clearCanvas(canvas, RECT); } private static void clearCanvas(Canvas canvas, RectF rect) { if (rect.width() <= 0 || rect.height() <= 0) { return; } canvas.drawRect(rect, PAINT); } }