直接继承自Android中原有控件
文章目录
渐变的TextView
效果:
代码:
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Shader;
import android.support.v7.widget.AppCompatTextView;
import android.util.AttributeSet;
import android.util.Log;
public class CustomTextView extends AppCompatTextView {
private final static String TAG = CustomTextView.class.getSimpleName();
private Paint paint1;
private Paint paint2;
private int mWidth;
private LinearGradient gradient;
private Matrix matrix;
//渐变的速度
private int deltaX;
public CustomTextView(Context context) {
super(context, null);
}
public CustomTextView(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context, attrs);
}
private void initView(Context context, AttributeSet attrs) {
paint1 = new Paint();
paint1.setColor(getResources().getColor(android.R.color.holo_blue_dark));
paint1.setStyle(Paint.Style.FILL);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
if(mWidth == 0){
Log.e(TAG,"*********************");
mWidth = getMeasuredWidth();
paint2 = getPaint();
//颜色渐变器
gradient = new LinearGradient(0, 0, mWidth, 0, new int[]{Color.GRAY,Color.WHITE,Color.GRAY}, new float[]{
0.3f,0.5f,1.0f
}, Shader.TileMode.CLAMP);
paint2.setShader(gradient);
matrix = new Matrix();
}
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if(matrix !=null){
deltaX += mWidth / 5;
if(deltaX > 2 * mWidth){
deltaX = -mWidth;
}
}
//关键代码通过矩阵的平移实现
matrix.setTranslate(deltaX, 0);
gradient.setLocalMatrix(matrix);
postInvalidateDelayed(100);
}
}