Android 重写Gallery 左对齐

修改xml成自定义的HorizontalGallery类：

package com.easyder.gotone.util;

import android.R.attr;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Camera;
import android.graphics.Matrix;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.Transformation;
import android.widget.Gallery;
public class HorizontalGallery extends Gallery {
	private Camera mCamera;
	private int mWidth;
	private int mPaddingLeft;
	private boolean flag;
	private static int firstChildWidth;
	private static int firstChildPaddingLeft;
	public HorizontalGallery(Context context) {
		super(context);
		mCamera = new Camera();
		this.setStaticTransformationsEnabled(true);
	}
	public HorizontalGallery(Context context, AttributeSet attrs) {
		super(context, attrs);
		mCamera = new Camera();
		// setAttributesValue(context, attrs);
		this.setStaticTransformationsEnabled(true);
	}
	public HorizontalGallery(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		mCamera = new Camera();
		// setAttributesValue(context, attrs);
		this.setStaticTransformationsEnabled(true);
	}
	private void setAttributesValue(Context context, AttributeSet attrs) {
		TypedArray typedArray = context.obtainStyledAttributes(attrs, new int[]{attr.paddingLeft});
		mPaddingLeft = typedArray.getDimensionPixelSize(0, 0);
		typedArray.recycle();
	}
	protected boolean getChildStaticTransformation(View child, Transformation t) {
		t.clear();
		t.setTransformationType(Transformation.TYPE_MATRIX);
		mCamera.save();
		final Matrix imageMatrix = t.getMatrix();
		final int imageHeight = child.getLayoutParams().height;
		final int imageWidth = child.getLayoutParams().width;
		if (flag) {
			firstChildWidth = getChildAt(0).getWidth();
			firstChildPaddingLeft = getChildAt(0).getPaddingLeft();
			flag = false;
		}
		mCamera.translate(firstChildWidth / 2 + firstChildPaddingLeft + mPaddingLeft - mWidth / 2, 0f, 0f);
		mCamera.getMatrix(imageMatrix);
		mCamera.restore();
		return true;
	}
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		if (!flag) {
			mWidth = w;
			getLayoutParams().width = mWidth;
			flag = true;
		}
		super.onSizeChanged(w, h, oldw, oldh);
	}
	@Override
	public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
		return false;
	}
	@Override
	public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
		return super.onScroll(e1, e2, distanceX, distanceY);
	}
}