使用GradientDrawable

最新推荐文章于 2024-11-05 15:13:53 发布
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#GradientDrawable #android
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本文提供了一个Android应用程序示例，展示了如何使用GradientDrawable类来创建带有渐变效果的矩形，并通过不同类型的渐变（线性、径向、扫掠）及角落圆角设置来丰富UI设计。
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/* 
 002 * Copyright (C) 2007 The Android Open Source Project
 
 003 *
 
 004 * Licensed under the Apache License, Version 2.0 (the "License");
 
 005 * you may not use this file except in compliance with the License.
 
 006 * You may obtain a copy of the License at
 
 007 *
 
 008 *       http://www.apache.org/licenses/LICENSE-2.0
 
 009 *
 
 010 * Unless required by applicable law or agreed to in writing, software
 
 011 * distributed under the License is distributed on an "AS IS" BASIS,
 
 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 
 013 * See the License for the specific language governing permissions and
 
 014 * limitations under the License.
 
 015 */
 
 016 
 
 017package app.test;
 
 018 
 
 019import android.app.Activity;
 
 020import android.content.Context;
 
 021import android.graphics.Canvas;
 
 022import android.graphics.Paint;
 
 023import android.graphics.Path;
 
 024import android.graphics.Picture;
 
 025import android.graphics.Rect;
 
 026import android.graphics.drawable.Drawable;
 
 027import android.graphics.drawable.GradientDrawable;
 
 028import android.os.Bundle;
 
 029import android.util.AttributeSet;
 
 030import android.view.View;
 
 031import android.view.ViewGroup;
 
 032import android.view.ViewParent;
 
 033 
 
 034public class Test extends  GraphicsActivity {
 
 035 
 
 036  @Override
 
 037  protected void onCreate(Bundle savedInstanceState) {
 
 038    super.onCreate(savedInstanceState);
 
 039    setContentView(new SampleView(this));
 
 040  }
 
 041 
 
 042  private static class  SampleView extends View {
 
 043    private Path mPath;
 
 044    private Paint mPaint;
 
 045    private Rect mRect;
 
 046    private GradientDrawable mDrawable;
 
 047 
 
 048    public SampleView(Context context) {
 
 049      super(context);
 
 050      setFocusable(true);
 
 051 
 
 052      mPath = new Path();
 
 053      mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
 
 054      mRect = new Rect(0, 0, 120, 120);
 
 055 
 
 056      mDrawable = new GradientDrawable(
 
 057          GradientDrawable.Orientation.TL_BR, new int[] { 0xFFFF0000,
 
 058              0xFF00FF00, 0xFF0000FF });
 
 059      mDrawable.setShape(GradientDrawable.RECTANGLE);
 
 060      mDrawable.setGradientRadius((float) (Math.sqrt(2) * 60));
 
 061    }
 
 062 
 
 063    static void setCornerRadii(GradientDrawable drawable, float r0,
 
 064        float r1, float  r2, float r3) {
 
 065      drawable.setCornerRadii(new float[] { r0, r0, r1, r1, r2, r2, r3,
 
 066          r3 });
 
 067    }
 
 068 
 
 069    @Override
 
 070    protected void onDraw(Canvas canvas) {
 
 071 
 
 072      mDrawable.setBounds(mRect);
 
 073 
 
 074      float r = 16;
 
 075 
 
 076      canvas.save();
 
 077      canvas.translate(10, 10);
 
 078      mDrawable.setGradientType(GradientDrawable.LINEAR_GRADIENT);
 
 079      setCornerRadii(mDrawable, r, r, 0, 0);
 
 080      mDrawable.draw(canvas);
 
 081      canvas.restore();
 
 082 
 
 083      canvas.save();
 
 084      canvas.translate(10 + mRect.width() + 10, 10);
 
 085      mDrawable.setGradientType(GradientDrawable.RADIAL_GRADIENT);
 
 086      setCornerRadii(mDrawable, 0, 0, r, r);
 
 087      mDrawable.draw(canvas);
 
 088      canvas.restore();
 
 089 
 
 090      canvas.translate(0, mRect.height() + 10);
 
 091 
 
 092      canvas.save();
 
 093      canvas.translate(10, 10);
 
 094      mDrawable.setGradientType(GradientDrawable.SWEEP_GRADIENT);
 
 095      setCornerRadii(mDrawable, 0, r, r, 0);
 
 096      mDrawable.draw(canvas);
 
 097      canvas.restore();
 
 098 
 
 099      canvas.save();
 
 100      canvas.translate(10 + mRect.width() + 10, 10);
 
 101      mDrawable.setGradientType(GradientDrawable.LINEAR_GRADIENT);
 
 102      setCornerRadii(mDrawable, r, 0, 0, r);
 
 103      mDrawable.draw(canvas);
 
 104      canvas.restore();
 
 105 
 
 106      canvas.translate(0, mRect.height() + 10);
 
 107 
 
 108      canvas.save();
 
 109      canvas.translate(10, 10);
 
 110      mDrawable.setGradientType(GradientDrawable.RADIAL_GRADIENT);
 
 111      setCornerRadii(mDrawable, r, 0, r, 0);
 
 112      mDrawable.draw(canvas);
 
 113      canvas.restore();
 
 114 
 
 115      canvas.save();
 
 116      canvas.translate(10 + mRect.width() + 10, 10);
 
 117      mDrawable.setGradientType(GradientDrawable.SWEEP_GRADIENT);
 
 118      setCornerRadii(mDrawable, 0, r, 0, r);
 
 119      mDrawable.draw(canvas);
 
 120      canvas.restore();
 
 121    }
 
 122  }
 
 123}
 
 124 
 
 125class GraphicsActivity extends Activity {
 
 126  // set to true to test Picture
 
 127  private static final  boolean TEST_PICTURE = false;
 
 128 
 
 129  @Override
 
 130  protected void onCreate(Bundle savedInstanceState) {
 
 131    super.onCreate(savedInstanceState);
 
 132  }
 
 133 
 
 134  @Override
 
 135  public void setContentView(View view) {
 
 136    if (TEST_PICTURE) {
 
 137      ViewGroup vg = new PictureLayout(this);
 
 138      vg.addView(view);
 
 139      view = vg;
 
 140    }
 
 141 
 
 142    super.setContentView(view);
 
 143  }
 
 144}
 
 145 
 
 146class PictureLayout extends ViewGroup {
 
 147  private final Picture mPicture =  new Picture();
 
 148 
 
 149  public PictureLayout(Context context) {
 
 150    super(context);
 
 151  }
 
 152 
 
 153  public PictureLayout(Context context, AttributeSet attrs) {
 
 154    super(context, attrs);
 
 155  }
 
 156 
 
 157  @Override
 
 158  public void addView(View child) {
 
 159    if (getChildCount() > 1) {
 
 160      throw new IllegalStateException(
 
 161          "PictureLayout can host only one direct child");
 
 162    }
 
 163 
 
 164    super.addView(child);
 
 165  }
 
 166 
 
 167  @Override
 
 168  public void addView(View child,  int index) {
 
 169    if (getChildCount() > 1) {
 
 170      throw new IllegalStateException(
 
 171          "PictureLayout can host only one direct child");
 
 172    }
 
 173 
 
 174    super.addView(child, index);
 
 175  }
 
 176 
 
 177  @Override
 
 178  public void addView(View child, LayoutParams params) {
 
 179    if (getChildCount() > 1) {
 
 180      throw new IllegalStateException(
 
 181          "PictureLayout can host only one direct child");
 
 182    }
 
 183 
 
 184    super.addView(child, params);
 
 185  }
 
 186 
 
 187  @Override
 
 188  public void addView(View child,  int index, LayoutParams params) {
 
 189    if (getChildCount() > 1) {
 
 190      throw new IllegalStateException(
 
 191          "PictureLayout can host only one direct child");
 
 192    }
 
 193 
 
 194    super.addView(child, index, params);
 
 195  }
 
 196 
 
 197  @Override
 
 198  protected LayoutParams generateDefaultLayoutParams() {
 
 199    return new LayoutParams(LayoutParams.MATCH_PARENT,
 
 200        LayoutParams.MATCH_PARENT);
 
 201  }
 
 202 
 
 203  @Override
 
 204  protected void onMeasure(int widthMeasureSpec, int  heightMeasureSpec) {
 
 205    final int count = getChildCount();
 
 206 
 
 207    int maxHeight = 0;
 
 208    int maxWidth = 0;
 
 209 
 
 210    for (int  i = 0; i < count; i++) {
 
 211      final View child = getChildAt(i);
 
 212      if (child.getVisibility() != GONE) {
 
 213        measureChild(child, widthMeasureSpec, heightMeasureSpec);
 
 214      }
 
 215    }
 
 216 
 
 217    maxWidth += getPaddingLeft() + getPaddingRight();
 
 218    maxHeight += getPaddingTop() + getPaddingBottom();
 
 219 
 
 220    Drawable drawable = getBackground();
 
 221    if (drawable != null) {
 
 222      maxHeight = Math.max(maxHeight, drawable.getMinimumHeight());
 
 223      maxWidth = Math.max(maxWidth, drawable.getMinimumWidth());
 
 224    }
 
 225 
 
 226    setMeasuredDimension(resolveSize(maxWidth, widthMeasureSpec),
 
 227        resolveSize(maxHeight, heightMeasureSpec));
 
 228  }
 
 229 
 
 230  private void drawPict(Canvas canvas,  int x, int y, int  w, int h, float sx,
 
 231      float sy) {
 
 232    canvas.save();
 
 233    canvas.translate(x, y);
 
 234    canvas.clipRect(0, 0, w, h);
 
 235    canvas.scale(0.5f, 0.5f);
 
 236    canvas.scale(sx, sy, w, h);
 
 237    canvas.drawPicture(mPicture);
 
 238    canvas.restore();
 
 239  }
 
 240 
 
 241  @Override
 
 242  protected void dispatchDraw(Canvas canvas) {
 
 243    super.dispatchDraw(mPicture.beginRecording(getWidth(), getHeight()));
 
 244    mPicture.endRecording();
 
 245 
 
 246    int x = getWidth() / 2;
 
 247    int y = getHeight() / 2;
 
 248 
 
 249    if (false) {
 
 250      canvas.drawPicture(mPicture);
 
 251    }  else {
 
 252      drawPict(canvas, 0, 0, x, y, 1, 1);
 
 253      drawPict(canvas, x, 0, x, y, -1, 1);
 
 254      drawPict(canvas, 0, y, x, y, 1, -1);
 
 255      drawPict(canvas, x, y, x, y, -1, -1);
 
 256    }
 
 257  }
 
 258 
 
 259  @Override
 
 260  public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
 
 261    location[0] = getLeft();
 
 262    location[1] = getTop();
 
 263    dirty.set(0, 0, getWidth(), getHeight());
 
 264    return getParent();
 
 265  }
 
 266 
 
 267  @Override
 
 268  protected void onLayout(boolean changed, int  l, int t, int r, int  b) {
 
 269    final int count = super.getChildCount();
 
 270 
 
 271    for (int  i = 0; i < count; i++) {
 
 272      final View child = getChildAt(i);
 
 273      if (child.getVisibility() != GONE) {
 
 274        final int childLeft = getPaddingLeft();
 
 275        final int childTop = getPaddingTop();
 
 276        child.layout(childLeft, childTop,
 
 277            childLeft + child.getMeasuredWidth(),
 
 278            childTop + child.getMeasuredHeight());
 
 279 
 
 280      }
 
 281    }
 
 282  }
 
 283}
 
 284 
 
 285    
 
 286     
 
 287   
 
288//该安卓代码来自于http://www.8jiaban.com/view/a9984631