2019.7.5更新，Android自定义点选验证码已完成。
先上效果图，没图说个蛋蛋：
ezgif-3-a89a55a08fab.gif
从效果图开始"临摹"
分析
从上面的效果图中，我们可以很直观的看出一共包含三个元素：背景图、空缺部分、填充部分，需要注意的是：
1. 空缺部分缺失的图片刚好是填充部分
2. 我们把填充部分位置固定在左侧，而随机生成空缺部分在右侧，增加验证难度
思路
- 准备背景图片，通过canvas.drawBitmap()方法画出背景图
- 计算View宽高，随机生成空缺部分的x坐标在（width/3, width）范围，固定填充部分的x左边在（0，width/3）范围内，保证填充部分和空缺部分在初始化时没有重叠。（不严谨，具体数值还要结合空缺部分/填充部分尺寸详细计算，仅提供思路）。
- 先随机生成空缺部分，然后根据空缺部分在原来Bitmap上的左边生成一样大小一样形状的图片，用于填充部分。
- 然后重写onTouchEvent方法，处理拖动时填充部分的位移，在MotionEvent.ACTION_UP条件下，计算填充部分和空缺部分在画布中的x坐标差值，判断当差值小于阙值 dx 时，则认为通过验证，否则调用 invalidate() 方法重新生成验证码。
主要代码分析
这里重写了onMeasure方法，根据我们准备的原图片尺寸设置View宽高，并且重新生成和View一样尺寸的背景图newBgBitmap，统一尺寸以便后面我们对左边的转化。(这里曾经有些地方参照画布尺寸计算，有些地方参照背景图bitmap尺寸计算，导致填充部分和空缺部分没有吻合)。
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int minimumWidth = getSuggestedMinimumWidth();
/*根据原背景图宽高比设置画布尺寸*/
width = measureSize(minimumWidth, widthMeasureSpec);
float scale = width / (float) bgBitmap.getWidth();
height = (int) (bgBitmap.getHeight() * scale);
setMeasuredDimension(width, height);
/*根据画布尺寸生成相同尺寸的背景图*/
newBgBitmap = clipBitmap(bgBitmap, width, height);
/*根据新的背景图生成填充部分*/
srcBitmap = createSmallBitmap(newBgBitmap);
}
设置画笔的混合模式，生成一张自定义形状的图片供填充部分使用
public Bitmap createSmallBitmap(Bitmap var) {
Bitmap bitmap = Bitmap.createBitmap(shadowSize, shadowSize, Bitmap.Config.ARGB_8888);
Canvas canvas1 = new Canvas(bitmap);
canvas1.drawCircle(shadowSize / 2, shadowSize / 2, shadowSize / 2, paintSrc);
/*设置混合模式*/
paintSrc.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
/*在指定范围随机生成空缺部分坐标，保证空缺部分出现在View右侧*/
int min = width / 3;
int max = width - shadowSize / 2 - padding;
Random random = new Random();
shadowLeft = random.nextInt(max) % (max - min + 1) + min;
Rect rect = new Rect(shadowLeft, (height - shadowSize) / 2, shadowSize + shadowLeft, (height + shadowSize) / 2);
RectF rectF = new RectF(0, 0, shadowSize, shadowSize);
canvas1.drawBitmap(var, rect, rectF, paintSrc);
paintSrc.setXfermode(null);
return bitmap;
}
在onDraw()方法中依次画出背景图、空缺部分、填充部分，注意先后顺序（具体细节自行处理，例如阴影、凹凸感等等）
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
RectF rectF = new RectF(0, 0, width, height);
/*画背景图*/
canvas.drawBitmap(newBgBitmap, null, rectF, paintSrc);
bgPaint.setColor(Color.parseColor("#000000"));
/*画空缺部分周围阴影*/
canvas.drawCircle(shadowLeft + shadowSize / 2, height / 2, shadowSize / 2, bgPaint);
/*画空缺部分*/
canvas.drawCircle(shadowLeft + shadowSize / 2, height / 2, shadowSize / 2, paintShadow);
Rect rect = new Rect(srcLeft, (height - shadowSize) / 2, shadowSize + srcLeft, (height + shadowSize) / 2);
bgPaint.setColor(Color.parseColor("#FFFFFF"));
/*画填充部分周围阴影*/
canvas.drawCircle(srcLeft + shadowSize / 2, height / 2, shadowSize / 2, bgPaint);
/*画填充部分*/
canvas.drawBitmap(srcBitmap, null, rect, paintSrc);
}
草纸代码参考
随写随发布😛
package com.example.qingfengwei.myapplication;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BlurMaskFilter;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;
import java.util.Random;
public class SlidingVerificationView extends View {
private Bitmap bgBitmap;
private Bitmap newBgBitmap;
private Bitmap srcBitmap;
private Paint paintShadow;
private Paint paintSrc;
private float curX;
private float lastX;
private int dx;
private int shadowSize = dp2px(60);
private int padding = dp2px(40);
private int shadowLeft;
private int srcLeft = padding;
private int width, height;
private Paint bgPaint;
private OnVerifyListener listener;
public SlidingVerificationView(Context context) {
this(context, null);
}
public SlidingVerificationView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public SlidingVerificationView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
paintShadow = new Paint();
paintShadow.setAntiAlias(true);
paintShadow.setColor(Color.parseColor("#AA000000"));
paintSrc = new Paint();
paintSrc.setAntiAlias(true);
paintSrc.setFilterBitmap(true);
paintSrc.setStyle(Paint.Style.FILL_AND_STROKE);
paintSrc.setColor(Color.WHITE);
bgPaint = new Paint();
bgPaint.setMaskFilter(new BlurMaskFilter(5, BlurMaskFilter.Blur.OUTER));
bgPaint.setAntiAlias(true);
bgPaint.setStyle(Paint.Style.FILL);
bgBitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.syzt);
}
public void setVerifyListener(OnVerifyListener listener) {
this.listener = listener;
}
public Bitmap clipBitmap(Bitmap bm, int newWidth, int newHeight) {
int width = bm.getWidth();
int height = bm.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
return Bitmap.createBitmap(bm, 0, 0, width, height, matrix, true);
}
public Bitmap createSmallBitmap(Bitmap var) {
Bitmap bitmap = Bitmap.createBitmap(shadowSize, shadowSize, Bitmap.Config.ARGB_8888);
Canvas canvas1 = new Canvas(bitmap);
canvas1.drawCircle(shadowSize / 2, shadowSize / 2, shadowSize / 2, paintSrc);
/*设置混合模式*/
paintSrc.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
/*在指定范围随机生成空缺部分坐标，保证空缺部分出现在View右侧*/
int min = width / 3;
int max = width - shadowSize / 2 - padding;
Random random = new Random();
shadowLeft = random.nextInt(max) % (max - min + 1) + min;
Rect rect = new Rect(shadowLeft, (height - shadowSize) / 2, shadowSize + shadowLeft, (height + shadowSize) / 2);
RectF rectF = new RectF(0, 0, shadowSize, shadowSize);
canvas1.drawBitmap(var, rect, rectF, paintSrc);
paintSrc.setXfermode(null);
return bitmap;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
curX = event.getRawX();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
lastX = event.getRawX();
break;
case MotionEvent.ACTION_MOVE:
dx = (int) (curX - lastX);
srcLeft = dx + padding;
invalidate();
break;
case MotionEvent.ACTION_UP:
boolean isSuccess = Math.abs(srcLeft - shadowLeft) < 8;
if (isSuccess) {
Toast.makeText(getContext(), "验证成功!", Toast.LENGTH_SHORT).show();
Log.d("w", "check success!");
} else {
Toast.makeText(getContext(), "验证失败!", Toast.LENGTH_SHORT).show();
Log.d("w", "check fail!");
srcBitmap = createSmallBitmap(newBgBitmap);
srcLeft = padding;
invalidate();
}
if (listener != null) {
listener.onResult(isSuccess);
}
break;
}
return true;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int minimumWidth = getSuggestedMinimumWidth();
/*根据原背景图宽高比设置画布尺寸*/
width = measureSize(minimumWidth, widthMeasureSpec);
float scale = width / (float) bgBitmap.getWidth();
height = (int) (bgBitmap.getHeight() * scale);
setMeasuredDimension(width, height);
/*根据画布尺寸生成相同尺寸的背景图*/
newBgBitmap = clipBitmap(bgBitmap, width, height);
/*根据新的背景图生成填充部分*/
srcBitmap = createSmallBitmap(newBgBitmap);
}
private int measureSize(int defaultSize, int measureSpec) {
int mode = MeasureSpec.getMode(measureSpec);
int size = MeasureSpec.getSize(measureSpec);
int result = defaultSize;
switch (mode) {
case MeasureSpec.UNSPECIFIED:
result = defaultSize;
break;
case MeasureSpec.AT_MOST:
case MeasureSpec.EXACTLY:
result = size;
break;
}
return result;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
RectF rectF = new RectF(0, 0, width, height);
/*画背景图*/
canvas.drawBitmap(newBgBitmap, null, rectF, paintSrc);
bgPaint.setColor(Color.parseColor("#000000"));
/*画空缺部分周围阴影*/
canvas.drawCircle(shadowLeft + shadowSize / 2, height / 2, shadowSize / 2, bgPaint);
/*画空缺部分*/
canvas.drawCircle(shadowLeft + shadowSize / 2, height / 2, shadowSize / 2, paintShadow);
Rect rect = new Rect(srcLeft, (height - shadowSize) / 2, shadowSize + srcLeft, (height + shadowSize) / 2);
bgPaint.setColor(Color.parseColor("#FFFFFF"));
/*画填充部分周围阴影*/
canvas.drawCircle(srcLeft + shadowSize / 2, height / 2, shadowSize / 2, bgPaint);
/*画填充部分*/
canvas.drawBitmap(srcBitmap, null, rect, paintSrc);
}
public static int dp2px(float dp) {
float density = Resources.getSystem().getDisplayMetrics().density;
return (int) (density * dp + 0.5f);
}
}
