Android开发之利用seekbar实现图片的旋转与缩放（一）

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在Android开发中，有时利用seekbar实现相关的图片的旋转与缩放；
这里就简单介绍一下，如何利用seekbar实现图片的放大与缩小；以及旋转。

这是布局代码：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/iv_1"
        android:layout_width="250dp"
        android:layout_height="250dp"
        android:layout_marginTop="16dp"
        android:src="@drawable/onmk"
        android:adjustViewBounds="true"
        android:layout_gravity="center"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/tv_1"
        android:layout_width="305dp"
        android:layout_height="38dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="12dp"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/iv_1" />

    <SeekBar
        android:id="@+id/sb_1"
        android:layout_width="match_parent"
        android:layout_height="31dp"
        android:layout_marginTop="12dp"
        android:progress="120"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="1.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/tv_1" />

    <TextView
        android:id="@+id/tv_2"
        android:layout_width="300dp"
        android:layout_height="38dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toTopOf="@+id/sb_2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/sb_1"
        app:layout_constraintVertical_bias="0.666" />

    <SeekBar
        android:id="@+id/sb_2"
        android:layout_width="match_parent"
        android:layout_height="31dp"
        android:layout_marginStart="4dp"
        android:layout_marginTop="60dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/sb_1" />

</android.support.constraint.ConstraintLayout>

主函数中的代码：

package com.example.wuluo.wlht;

/**
 * Created by wuluo on 2019/3/9
 */
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.DisplayMetrics;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.SeekBar;
import android.widget.TextView;
import android.graphics.Matrix;

public class MainActivity extends AppCompatActivity implements SeekBar.OnSeekBarChangeListener {
    private ImageView iv_1;
    private SeekBar sb_1,sb_2;
    private Matrix matrix;
    private TextView tv_1,tv_2;
    private int minWidth = 80;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        iv_1=(ImageView) findViewById(R.id.iv_1);
        sb_1=(SeekBar)findViewById(R.id.sb_1);
        sb_2=(SeekBar)findViewById(R.id.sb_2);
        tv_1=(TextView)findViewById(R.id.tv_1);
        tv_2=(TextView)findViewById(R.id.tv_2);
        sb_1.setOnSeekBarChangeListener(this);
        sb_2.setOnSeekBarChangeListener(this);
        matrix=new Matrix();

        //屏幕宽度
        DisplayMetrics dm=new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);
        int screen=dm.widthPixels;
        //设置硕放滑动最大值
        sb_1.setMax(screen);
        sb_2.setMax(365);


    }

    @Override
    public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
        if(seekBar.getId()==R.id.sb_1){
            int newWidth = i + minWidth;
            int newHeight = (int) (newWidth * 3 / 4);//按照原图片的比例缩放
            iv_1.setLayoutParams(new LinearLayout.LayoutParams(newWidth, newHeight));
            tv_1.setText("图像宽度：" + newWidth + " 图像高度：" + newHeight);

            /*int ivWidth=i;
            int ivHeight=i*3/4;
            iv_1.setLayoutParams(new LinearLayout.LayoutParams(ivWidth,ivHeight));*/
        }else if (seekBar.getId()==R.id.sb_2){
            float d=i;
            matrix.setRotate(d);
            Bitmap bitmap=BitmapFactory.decodeResource(getResources(),R.drawable.bnvx);
            Bitmap bitmap1 = bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
            iv_1.setImageBitmap(bitmap1);
            tv_2.setText(i+"度");
        }
    }

    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {


    }

    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {

    }
}

实现效果：

样式挺简单的，效果也比较简单，
目前只是针对一张图片，后面会添加其他功能！