AndroidのUI - ImageView - liguofeng29’s blog

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center">
        <Button
            android:id="@+id/plus_alpha"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="透明度+"/>
        <Button
            android:id="@+id/minus_alpha"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="透明度-"/>
        <Button
            android:id="@+id/next"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="次の画像" />
    </LinearLayout>
    <ImageView
        android:id="@+id/image1"
        android:layout_width="match_parent"
        android:layout_height="280dp"
        android:scaleType="fitCenter"
        android:src="@drawable/a"
        />
    <ImageView
        android:id="@+id/image2"
        android:layout_width="120dp"
        android:layout_height="120dp"
        android:background="#0000ff"
        android:layout_margin="10pt"
        />
</LinearLayout>

MainActivity.xml

package com.example.liguofeng.imageview;

import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {

    private int[] images = new int[]{
            R.drawable.a,
            R.drawable.b,
            R.drawable.c,
            R.drawable.d,
            R.drawable.e
    };

    private Button next;
    private int currentImage = 0; // 現在の画像
    private int alpha = 255; // 透明度

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        next = (Button) findViewById(R.id.next);
        final Button plus = (Button) findViewById(R.id.plus_alpha);
        final Button minus = (Button) findViewById(R.id.minus_alpha);

        final ImageView image1 = (ImageView) findViewById(R.id.image1);
        final ImageView image2 = (ImageView) findViewById(R.id.image2);

        next.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 次の画像表示
                image1.setImageResource(images[++currentImage % images.length]);
            }
        });

        View.OnClickListener listner = new View.OnClickListener()
            {@Override
            public void onClick(View e) {
                if (e == plus) {
                    alpha += 20;
                }
                if (e == minus) {
                    alpha -= 20;
                }
                if (alpha >= 255) {
                    alpha = 255;
                }
                if(alpha <= 0) {
                    alpha = 0;
                }

                // 透明度変更
                image1.setImageAlpha(alpha);
            }
        };

        // イベント設定
        plus.setOnClickListener(listner);
        minus.setOnClickListener(listner);

        image1.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                BitmapDrawable bitmapDrawable = (BitmapDrawable) image1.getDrawable();
                Bitmap bitmap = bitmapDrawable.getBitmap();

                // bitmap実際サイズとimages1の伸縮比例
                double scale = 1.0 * bitmap.getHeight() / image1.getHeight();

                int x = (int) (event.getX() * scale);
                int y = (int) (event.getY() * scale);

                if( x + 120 > bitmap.getWidth() ) {
                    x = bitmap.getWidth() - 120;
                }
                if(y + 120 > bitmap.getHeight() ) {
                    y = bitmap.getHeight() - 120;
                }

                // image2設定
                image2.setImageBitmap(Bitmap.createBitmap(bitmap, x, y, 120, 120));
                image2.setImageAlpha(alpha);

                return false;
            }
        });
    }
}