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Android example source code file (TransformTestActivity.java)

This example Android source code file (TransformTestActivity.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

android, displaymetrics, drawable, drawing, graphics, linearlayout, listener, matrix, override, paint, scalegesturedetector, transformtestactivity, transformview, ui, view

The TransformTestActivity.java Android example source code

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.test.transform;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.LinearLayout;

public class TransformTestActivity extends Activity {
    public TransformTestActivity() {
        super();
        init(false);
    }
    
    public TransformTestActivity(boolean noCompat) {
        super();
        init(noCompat);
    }
    
    public void init(boolean noCompat) {

    }
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        this.setTitle(R.string.act_title);
        LinearLayout root = new LinearLayout(this);
        root.setOrientation(LinearLayout.VERTICAL);

        TransformView view = new TransformView(getApplicationContext());
        Drawable drawable = getResources().getDrawable(R.drawable.logo);
        drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicWidth());
        view.setDrawable(drawable);

        root.addView(view);
        setContentView(root);
    }
    
    private class TransformView extends View {
        private Drawable mDrawable;
        private float mPosX;
        private float mPosY;
        private float mScale = 1.f;
        private Matrix mMatrix;
        private ScaleGestureDetector mDetector;
        
        private float mLastX;
        private float mLastY;
        
        private class Listener implements ScaleGestureDetector.OnScaleGestureListener {

            public boolean onScale(ScaleGestureDetector detector) {
                float scale = detector.getScaleFactor();
                
                Log.d("ttest", "Scale: " + scale);
                
                // Limit the scale so our object doesn't get too big or disappear
                if (mScale * scale > 0.1f) {
                    if (mScale * scale < 10.f) {
                        mScale *= scale;
                    } else {
                        mScale = 10.f;
                    }
                } else {
                    mScale = 0.1f;
                }
                
                Log.d("ttest", "mScale: " + mScale + " mPos: (" + mPosX + ", " + mPosY + ")");
                
                float sizeX = mDrawable.getIntrinsicWidth()/2;
                float sizeY = mDrawable.getIntrinsicHeight()/2;
                float centerX = detector.getFocusX();
                float centerY = detector.getFocusY();
                float diffX = centerX - mPosX;
                float diffY = centerY - mPosY;
                diffX = diffX*scale - diffX;
                diffY = diffY*scale - diffY;
                mPosX -= diffX;
                mPosY -= diffY;
                mMatrix.reset();
                mMatrix.postTranslate(-sizeX, -sizeY);
                mMatrix.postScale(mScale, mScale);
                mMatrix.postTranslate(mPosX, mPosY);
                                
                invalidate();

                return true;
            }

            public boolean onScaleBegin(ScaleGestureDetector detector) {
                return true;
            }

            public void onScaleEnd(ScaleGestureDetector detector) {
                mLastX = detector.getFocusX();
                mLastY = detector.getFocusY();
            }            
        }
        
        public TransformView(Context context) {
            super(context);
            mMatrix = new Matrix();
            mDetector = new ScaleGestureDetector(context, new Listener());
            DisplayMetrics metrics = context.getResources().getDisplayMetrics();
            mPosX = metrics.widthPixels/2;
            mPosY = metrics.heightPixels/2;
        }
        
        public void setDrawable(Drawable d) {
            mDrawable = d;
            
            float sizeX = mDrawable.getIntrinsicWidth()/2;
            float sizeY = mDrawable.getIntrinsicHeight()/2;
            mMatrix.reset();
            mMatrix.postTranslate(-sizeX, -sizeY);
            mMatrix.postScale(mScale, mScale);
            mMatrix.postTranslate(mPosX, mPosY);
        }
        
        @Override
        public boolean onTouchEvent(MotionEvent event) {
            mDetector.onTouchEvent(event);
            
            // Handling single finger pan
            if (!mDetector.isInProgress()) {
                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        mLastX = event.getX();
                        mLastY = event.getY();
                        break;
                        
                    case MotionEvent.ACTION_MOVE:
                        final float x = event.getX();
                        final float y = event.getY();
                        mPosX += x - mLastX;
                        mPosY += y - mLastY;
                        mLastX = x;
                        mLastY = y;
                        
                        float sizeX = mDrawable.getIntrinsicWidth()/2;
                        float sizeY = mDrawable.getIntrinsicHeight()/2;
                        
                        mMatrix.reset();
                        mMatrix.postTranslate(-sizeX, -sizeY);
                        mMatrix.postScale(mScale, mScale);
                        mMatrix.postTranslate(mPosX, mPosY);
                        invalidate();
                        break;
                }
            }

            return true;
        }
        
        @Override
        public void onDraw(Canvas canvas) {
            int saveCount = canvas.getSaveCount();
            canvas.save();
            canvas.concat(mMatrix);
            mDrawable.draw(canvas);
            canvas.restoreToCount(saveCount);
        }
    }
}

Other Android examples (source code examples)

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