[Android] Android 按鈕按下、彈起狀態及簡單應用

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●要讓按鈕按下或彈起其實非常簡單，用OnTouchListener監聽，
並在裡面判斷按下及彈起事件


先貼上簡單的程式碼 


package com.learn;

import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {
private Button touch;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
touch = (Button) findViewById(R.id.button1);
touch.setOnTouchListener(touchlistener);
}

Button.OnTouchListener touchlistener = new Button.OnTouchListener() {

@Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
touch.setText("按下");

} else if (event.getAction() == MotionEvent.ACTION_UP) {
touch.setText("彈起");
}
return false;
}
};

}





沒按下顯示我是一顆普通按鈕 ，按下去不放開顯示按下，放開則顯示彈起

 結果圖

●另外我們可以用這方法去實現一些效果，字體顏色改變、放大縮小、圖片變換等等...
以下是改變圖片大小，以縮放的方式去呈現

代碼
Button.OnTouchListener changeListener = new Button.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
float scaleWidth = 0;
float scaleHeight = 0;
if (event.getAction() == MotionEvent.ACTION_DOWN) {

img.buildDrawingCache();
Bitmap bmp = img.getDrawingCache();
int width = bmp.getWidth();
int height = bmp.getHeight();
// 放大為1.2倍
scaleWidth = (float) 1.2;
scaleHeight = (float) 1.2;

Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Bitmap newbm = Bitmap.createBitmap(bmp, 0, 0, width, height,
matrix, true);
img.setImageBitmap(newbm);

} else if (event.getAction() == MotionEvent.ACTION_UP) {
img.buildDrawingCache();
Bitmap bmp = img.getDrawingCache();

int width = bmp.getWidth();
int height = bmp.getHeight();

scaleWidth = (float) 0.85;
scaleHeight = (float) 0.85;
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);

Bitmap newbm = Bitmap.createBitmap(bmp, 0, 0, width, height,
matrix, true);

img.setImageBitmap(newbm);

}
return false;
}

};
 結果圖

 

●改變字體大小及顏色，顏色有兩種方式可以實作
1.把顏色寫程式碼內
Button.OnTouchListener textlistener = new Button.OnTouchListener() {

@Override
public boolean onTouch(View v, MotionEvent event) {
Color c = null ;
if (event.getAction() == MotionEvent.ACTION_DOWN) {
text.setText("放大，藍色");
tv.setTextSize(30);
tv.setTextColor(c.BLUE);
 
} else if (event.getAction() == MotionEvent.ACTION_UP) {
text.setText("縮小，黑色");
tv.setTextSize(20);
tv.setTextColor(c.BLACK);

}
return false;
}

};
2.把顏色在styles 資源檔裡

Button.OnTouchListener textlistener = new Button.OnTouchListener() {

@Override
public boolean onTouch(View v, MotionEvent event) {

if (event.getAction() == MotionEvent.ACTION_DOWN) {
text.setText("放大，藍色");
tv.setTextSize(30);
tv.setTextColor(getResources().getColor(R.color.blue));
   
} else if (event.getAction() == MotionEvent.ACTION_UP) {
text.setText("縮小，黑色");
tv.setTextSize(20);
tv.setTextColor(getResources().getColor(R.color.black));
效果圖

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