Java tutorial
package com.gavin.refreshlayout.refreshwidget; /* * Copyright (C) 2014 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. */ import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.RadialGradient; import android.graphics.Shader; import android.graphics.drawable.ShapeDrawable; import android.graphics.drawable.shapes.OvalShape; import android.support.v4.view.ViewCompat; import android.view.animation.Animation; import android.widget.ImageView; /** * Private class created to work around issues with AnimationListeners being * called before the animation is actually complete and support shadows on older * platforms. * * @hide */ class CircleImageView extends ImageView { private static final int KEY_SHADOW_COLOR = 0x1E000000; private static final int FILL_SHADOW_COLOR = 0x3D000000; // PX private static final float X_OFFSET = 0f; private static final float Y_OFFSET = 1.75f; private static final float SHADOW_RADIUS = 3.5f; private static final int SHADOW_ELEVATION = 4; private Animation.AnimationListener mListener; private int mShadowRadius; public CircleImageView(Context context, int color, final float radius) { super(context); final float density = getContext().getResources().getDisplayMetrics().density; final int diameter = (int) (radius * density * 2); final int shadowYOffset = (int) (density * Y_OFFSET); final int shadowXOffset = (int) (density * X_OFFSET); mShadowRadius = (int) (density * SHADOW_RADIUS); ShapeDrawable circle; if (elevationSupported()) { circle = new ShapeDrawable(new OvalShape()); ViewCompat.setElevation(this, SHADOW_ELEVATION * density); } else { OvalShape oval = new OvalShadow(mShadowRadius, diameter); circle = new ShapeDrawable(oval); ViewCompat.setLayerType(this, ViewCompat.LAYER_TYPE_SOFTWARE, circle.getPaint()); circle.getPaint().setShadowLayer(mShadowRadius, shadowXOffset, shadowYOffset, KEY_SHADOW_COLOR); final int padding = mShadowRadius; // set padding so the inner image sits correctly within the shadow. setPadding(padding, padding, padding, padding); } circle.getPaint().setColor(color); setBackgroundDrawable(circle); } private boolean elevationSupported() { return android.os.Build.VERSION.SDK_INT >= 21; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); if (!elevationSupported()) { setMeasuredDimension(getMeasuredWidth() + mShadowRadius * 2, getMeasuredHeight() + mShadowRadius * 2); } } public void setAnimationListener(Animation.AnimationListener listener) { mListener = listener; } @Override public void onAnimationStart() { super.onAnimationStart(); if (mListener != null) { mListener.onAnimationStart(getAnimation()); } } @Override public void onAnimationEnd() { super.onAnimationEnd(); if (mListener != null) { mListener.onAnimationEnd(getAnimation()); } } /** * Update the background color of the circle image view. * * @param colorRes Id of a color resource. */ public void setBackgroundColorRes(int colorRes) { setBackgroundColor(getContext().getResources().getColor(colorRes)); } @Override public void setBackgroundColor(int color) { if (getBackground() instanceof ShapeDrawable) { ((ShapeDrawable) getBackground()).getPaint().setColor(color); } } private class OvalShadow extends OvalShape { private RadialGradient mRadialGradient; private Paint mShadowPaint; private int mCircleDiameter; public OvalShadow(int shadowRadius, int circleDiameter) { super(); mShadowPaint = new Paint(); mShadowRadius = shadowRadius; mCircleDiameter = circleDiameter; mRadialGradient = new RadialGradient(mCircleDiameter / 2, mCircleDiameter / 2, mShadowRadius, new int[] { FILL_SHADOW_COLOR, Color.TRANSPARENT }, null, Shader.TileMode.CLAMP); mShadowPaint.setShader(mRadialGradient); } @Override public void draw(Canvas canvas, Paint paint) { final int viewWidth = CircleImageView.this.getWidth(); final int viewHeight = CircleImageView.this.getHeight(); canvas.drawCircle(viewWidth / 2, viewHeight / 2, (mCircleDiameter / 2 + mShadowRadius), mShadowPaint); canvas.drawCircle(viewWidth / 2, viewHeight / 2, (mCircleDiameter / 2), paint); } } }