Custom Scrollable Image View

It is a pain to have an image view horizontal and vertical scroll. Here is a custom scroll image view class. Edit: This is a more efficient implementation and also conforms to parent constraints. Text Box package com.amphro.receptionmapper; import android.content.Context; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Paint; import android.util.AttributeSet; import android.view.Display; import android.view.MotionEvent; import android.view.View; import android.view.WindowManager; public class ScrollImageView extends View { private final int DEFAULT_PADDING = 10; private Display mDisplay; private Bitmap mImage; /* Current x and y of the touch */ private float mCurrentX = 0; private float mCurrentY = 0; private float mTotalX = 0; private float mTotalY = 0; /* The touch distance change from the current touch */ private float mDeltaX = 0; private float mDeltaY = 0; int mDisplayWidth; int mDisplayHeight; int mPadding; public ScrollImageView(Context context) { super(context); initScrollImageView(context); } public ScrollImageView(Context context, AttributeSet attributeSet) { super(context); initScrollImageView(context); } private void initScrollImageView(Context context) { mDisplay = ((WindowManager)context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay(); mPadding = DEFAULT_PADDING; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int width = measureDim(widthMeasureSpec, mDisplay.getWidth()); int height = measureDim(heightMeasureSpec, mDisplay.getHeight()); setMeasuredDimension(width, height); } private int measureDim(int measureSpec, int size) {         int result = 0;         int specMode = MeasureSpec.getMode(measureSpec);         int specSize = MeasureSpec.getSize(measureSpec);         if (specMode == MeasureSpec.EXACTLY) {             result = specSize;         } else {             result = size;             if (specMode == MeasureSpec.AT_MOST) {                result = Math.min(result, specSize);             }         }         return result;     } public Bitmap getImage() { return mImage; } public void setImage(Bitmap image) { mImage = image; } public int getPadding() { return mPadding; } public void setPadding(int padding) { this.mPadding = padding; } @Override public boolean onTouchEvent(MotionEvent event) { if (event.getAction() == MotionEvent.ACTION_DOWN) { mCurrentX = event.getRawX(); mCurrentY = event.getRawY(); }  else if (event.getAction() == MotionEvent.ACTION_MOVE) { float x = event.getRawX(); float y = event.getRawY(); // Update how much the touch moved mDeltaX = x - mCurrentX; mDeltaY = y - mCurrentY; mCurrentX = x; mCurrentY = y; invalidate(); } // Consume event return true; } @Override protected void onDraw(Canvas canvas) { if (mImage == null) { return; } float newTotalX = mTotalX + mDeltaX; // Don't scroll off the left or right edges of the bitmap. if (mPadding > newTotalX && newTotalX > getMeasuredWidth() - mImage.getWidth() - mPadding) mTotalX += mDeltaX; float newTotalY = mTotalY + mDeltaY; // Don't scroll off the top or bottom edges of the bitmap. if (mPadding > newTotalY && newTotalY > getMeasuredHeight() - mImage.getHeight() - mPadding) mTotalY += mDeltaY; Paint paint = new Paint(); canvas.drawBitmap(mImage, mTotalX, mTotalY, paint); } }