Android开发（六）
绘制文本
绘制类 借助 Canvas 类进行绘制
通过重写View.onDraw 方法来进行旁白描绘
package com.mingrisoft;
import android.app.Fragment;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Shader;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.RelativeLayout;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FrameLayout fragment = (FrameLayout) findViewById(R.id.frameLayout); //获取帧布局管理器
fragment.addView(new MyView(this)); //将自定义视图的内部类添加到布局管理器中
}
private class MyView extends View {
public MyView(Context context) {
super(context);
}
@Override
protected void onDraw(Canvas canvas) { //重写onDraw()方法
Paint paint = new Paint(); //定义一个默认的画笔
//线性渐变
Shader shader = new LinearGradient(0, 0, 100, 100,
Color.RED, Color.GREEN, Shader.TileMode.MIRROR);
paint.setShader(shader); //为画笔设置渐变器
canvas.drawRect(10, 10, 280, 150, paint); //绘制矩形
super.onDraw(canvas);
}
}
}
绘制图片
- 创建位图对象， JAVA 中bitmap 表示位图对象
创建位图对象 两种方式：- BitMapFactory : 1. 通过图片文件创建 2.通过输入流创建
2） BitMap 类 挖取一块图像创建， 将源位图缩放生成， 使用颜色数组创建
BitMapFactory： 1.decodeFile, 2.decodeResource, 3.decodeStream
访问SDK资源需要在Mainiefiest.xml 配置访问权限 ，2.同时在Android 上配置访问权限
- BitMapFactory : 1. 通过图片文件创建 2.通过输入流创建
package com.example.myapplication;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.FrameLayout;
import androidx.appcompat.app.AppCompatActivity;
/**
* 手势方式滑动动画
*/
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FrameLayout frameLayout= (FrameLayout) findViewById(R.id.frameLayout); //获取帧布局管理器
frameLayout.addView(new MyView(this)); //将自定义视图的内部类添加到布局管理器中
}
}
class MyView extends View {
public MyView(Context context) {
super(context);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 获取SDK上 图片绘制
String path = Environment.getExternalStorageDirectory() + "/snail.png";
Bitmap bitmap = BitmapFactory.decodeFile(path);
//通过 canvas 类 绘制图片
Paint paint = new Paint(); //定义
canvas.drawBitmap(bitmap,150,150, paint);
// 从图像中挖取一小片 bitMap 类 的 createBitMap(截取一小块), compress(压缩)
// 从原始图像挖取小部分
Bitmap bitmap1 = Bitmap.createBitmap(bitmap,23,89,150,168);
canvas.drawBitmap(bitmap1,270,50, paint);
}
}
绘制路径
- 通过绘制路径
- 通过绘制路径的文字
package com.example.myapplication;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.view.View;
import android.widget.FrameLayout;
import androidx.appcompat.app.AppCompatActivity;
/**
*
*/
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FrameLayout frameLayout= (FrameLayout) findViewById(R.id.frameLayout); //获取帧布局管理器
frameLayout.addView(new MyView(this)); //将自定义视图的内部类添加到布局管理器中
}
}
/**
* 绘制路径
* */
class MyView extends View {
public MyView(Context context) {
super(context);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = new Paint();
paint.setAntiAlias(true) ; // 定义抗锯齿
paint.setColor(0xFF0000FF);
paint.setStyle(Paint.Style.STROKE); // 设置样式为描边
Path path = new Path();
// 最后一个参数环按照 顺时针还是
path.addCircle(150,100,50,Path.Direction.CW);
// canvas.drawPath(path,paint);
canvas.drawTextOnPath("活着就是为了修改时间", path,0,0,paint);
}
}
逐帧动画
- 创建动画资源文件 在drawable 目录下面
使用 animation-list
<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/img001" android:duration="60"/>
<item android:drawable="@drawable/img002" android:duration="60"/>
<item android:drawable="@drawable/img003" android:duration="60"/>
<item android:drawable="@drawable/img004" android:duration="60"/>
<item android:drawable="@drawable/img005" android:duration="60"/>
<item android:drawable="@drawable/img006" android:duration="60"/>
</animation-list>
- MainActivity 获取AnminationDrawable 方法设置动态图逐帧播放
package com.example.myapplication;
import android.graphics.drawable.AnimationDrawable;
import android.os.Bundle;
import android.view.View;
import android.widget.LinearLayout;
import androidx.appcompat.app.AppCompatActivity;
/**
*
*/
public class MainActivity extends AppCompatActivity {
private boolean flag = true;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LinearLayout linearLayout= (LinearLayout) findViewById(R.id.linearLayout); //获取布局管理器
//获取AnimationDrawable对象
final AnimationDrawable anim = (AnimationDrawable) linearLayout.getBackground();
linearLayout.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view) {
if(flag){
anim.start();
flag = false;
}else{
anim.stop();
flag = true;
}
}
});
}
}
补间动画
- 通过手势滑动查看相片的手机相册
- 创建一个动画资源
参考手势时候 设置动画资源文件
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<alpha android:fromAlpha="0"
android:toAlpha="1"
android:duration="4000"/>
</set>
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<alpha android:fromAlpha="1"
android:toAlpha="0"
android:duration="2000"/>
</set>
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<scale android:fromXScale="0.0"
android:fromYScale="0.0"
android:pivotX="50%"
android:pivotY="50%"
android:toXScale="1.0"
android:toYScale="1.0"
android:duration="2000"></scale>
</set>
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<scale android:fromXScale="1.0"
android:fromYScale="1.0"
android:pivotX="50%"
android:pivotY="50%"
android:toXScale="0.0"
android:toYScale="0.0"
android:duration="2000"></scale>
</set>
- 定义并且初始化动画数组
- 指定切换的动画效果
package com.example.myapplication;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.ViewFlipper;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity implements GestureDetector.OnGestureListener {
ViewFlipper flipper; //定义ViewFlipper
GestureDetector detector; //定义手势检测器
Animation[] animation = new Animation[4];//定义动画数组，为ViewFlipper指定切换动画
final int distance = 50; //定义手势动作两点之间最小距离
//定义图片数组
private int[] images = new int[]{R.drawable.img01, R.drawable.img02, R.drawable.img03,
R.drawable.img04, R.drawable.img05, R.drawable.img06, R.drawable.img07, R.drawable.img08,
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
detector = new GestureDetector(this, this); //创建手势检测器
flipper = (ViewFlipper) findViewById(R.id.flipper); //获取ViewFlipper
for (int i = 0; i < images.length; i++) {
ImageView imageView = new ImageView(this);
imageView.setImageResource(images[i]);
flipper.addView(imageView); //加载图片
}
//初始化动画数组
animation[0] = AnimationUtils.loadAnimation(this, R.anim.anim_alpha_in); //淡入动画
animation[1] = AnimationUtils.loadAnimation(this, R.anim.anim_alpha_out); //淡出动画
animation[2] = AnimationUtils.loadAnimation(this, R.anim.anim_scale_in); //放大进入动画
animation[3] = AnimationUtils.loadAnimation(this, R.anim.anim_scale_out); //缩小退出动画
}
@Override
public boolean onDown(MotionEvent e) {
return false;
}
@Override
public void onShowPress(MotionEvent e) {
}
@Override
public boolean onSingleTapUp(MotionEvent e) {
return false;
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
return false;
}
@Override
public void onLongPress(MotionEvent e) {
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
/*
如果第一个触点事件的X坐标到第二个触点事件的X坐标的距离超过distance就是从右向左滑动
*/
if (e1.getX() - e2.getX() > distance) {
//为flipper设置切换的动画效果
flipper.setInAnimation(animation[0]);
flipper.setOutAnimation(animation[1]);
flipper.showPrevious();
return true;
/*
如果第二个触点事件的X坐标到第一个触点事件的X坐标的距离超过distance就是从左向右滑动
*/
} else if (e2.getX() - e1.getX() > distance) {
//为flipper设置切换的动画
flipper.setInAnimation(animation[2]);
flipper.setOutAnimation(animation[3]);
flipper.showNext();
return true;
}
return false;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//将该Activity上的触碰事件交给GestureDetector处理
return detector.onTouchEvent(event);
}
}