Android自定义控件 ----- 基本绘制流程，简单控件的实现

一、自定义控件（一） --- 自定义属性TextView

1，定义属性，制作attrs.xml文件；

    属性值：

string,color,attr,array,bool,declare-styleable,dimen,drawable,eat-comment,fraction,

integer,integer-array,item,plurals,string-array,style

    属性取值范围：

string,color,demension,integer,enum,reference,float,boolean,fraction,flag;

2，重写构造方法【1，2，3参数，重写三参数】

    获取View属性值，实现基本的布局

    /**
     * 文本
     */
    private String mTitleText;
    /**
     * 文本的颜色
     */
    private int mTitleTextColor;
    /**
     * 文本的大小
     */
    private int mTitleTextSize;

    /**
     * 绘制时控制文本绘制的范围
     */
    private Rect mBound;
    /**
     * 画笔
     */
    private Paint mPaint;


    /**
     * 构造方法
     *
     * @param context
     * @param attrs
     */
    public CustomTitleView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    /**
     * 构造方法
     *
     * @param context
     */
    public CustomTitleView(Context context) {
        this(context, null);
    }

    /**
     * 获得我自定义的样式属性
     *
     * @param context
     * @param attrs
     * @param defStyle
     */
    public CustomTitleView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        /**
         * 添加事件【第五步时，把这一块代码加入】
         */
        this.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                mTitleText = randomText();
                postInvalidate();
            }

        });
        /**
         * 获得我们所定义的自定义样式属性
         */
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomTitleView, defStyle, 0);
        int n = a.getIndexCount();
        for (int i = 0; i < n; i++) {
            int attr = a.getIndex(i);
            switch (attr) {
                case R.styleable.CustomTitleView_titleText:
                    mTitleText = a.getString(attr);
                    break;
                case R.styleable.CustomTitleView_titleTextColor:
                    // 默认颜色设置为黑色
                    mTitleTextColor = a.getColor(attr, Color.BLACK);
                    break;
                case R.styleable.CustomTitleView_titleTextSize:
                    // 默认设置为16sp，TypeValue也可以把sp转化为px
                    mTitleTextSize = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(
                            TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics()));
                    break;
            }
        }
        a.recycle();

        /**
         * 获得绘制文本的宽和高
         */
        mPaint = new Paint();
        mPaint.setTextSize(mTitleTextSize);
        mPaint.setColor(mTitleTextColor);
        mBound = new Rect();
        mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound);

    }

3，重写onDraw()方法，绘制View

    paint绘制view到canvas上【将view用笔绘制到画布上】

    @Override
    protected void onDraw(Canvas canvas) {
        mPaint.setColor(Color.YELLOW);
        canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint);

        mPaint.setColor(mTitleTextColor);
        canvas.drawText(mTitleText, getWidth() / 2 - mBound.width() / 2, getHeight() / 2 + mBound.height() / 2, mPaint);
    }

4，重写onMeasure()方法

    实现将所有View重新布局【摆放】

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        /**
         * 1，不重写该方法，系统默认填充父窗体
         */
//        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        /**
         * 2, 重写当前方法
         */
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);
        int width;
        int height;
        /**
         * 宽度获取
         */
        if (widthMode == MeasureSpec.EXACTLY) {
            width = widthSize;
        } else {
            mPaint.setTextSize(mTitleTextSize);
            mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound);
            float textWidth = mBound.width();
            int desired = (int) (getPaddingLeft() + textWidth + getPaddingRight());
            width = desired;
        }

        /**
         * 高度获取
         */
        if (heightMode == MeasureSpec.EXACTLY) {
            height = heightSize;
        } else {
            mPaint.setTextSize(mTitleTextSize);
            mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound);
            float textHeight = mBound.height();
            int desired = (int) (getPaddingTop() + textHeight + getPaddingBottom());
            height = desired;
        }

        setMeasuredDimension(width, height);
    }

5，添加控件的响应事件

    添加事件触发器

    实现事件的具体响应

    /**
     * 生成随机文字【也可以实现其他的事件，管理控件属性】
     *
     * @return
     */
    private String randomText() {
        Random random = new Random();
        Set set = new HashSet();
        while (set.size() < 4) {
            int randomInt = random.nextInt(10);
            set.add(randomInt);
        }
        StringBuffer sb = new StringBuffer();
        for (Integer i : set) {
            sb.append("" + i);
        }
        return sb.toString();
    }

在使用命名空间时：

xmlns:test=" http://schemas.android.com/apk/res-auto"  在AS中使用

xmlns:test=" http://schemas.android.com/apk/res/[你的包名]"

http://www.imooc.com/video/8302  慕课网【推荐学习】

二、自定义控件（二） --- 属性TextView联合图片

自定义控件的基本步骤：

1、自定义View的属性
2、在View的构造方法中获得我们自定义的属性
[ 3、重写onMesure ]  //可选项
4、重写onDraw

在绘制过程中，控制内容大小。

扩展：

        为自定义控件添加触发事件；

        为自定义控件添加整体响应【事件机制，返回，Home处理】

/**
 * 类说明：带图片说明的ImageView控件
 * 作者：vision
 * 时间：2016/7/15
 */
public class CustomImageView extends View {
    /**
     * 标识图片当前缩放模式
     */
    private static final int IMAGE_SCALE_FITXY = 0;
    /**
     * 文本
     */
    private String mTitle;
    /**
     * 文本的颜色
     */
    private int mTextColor;
    /**
     * 文本的大小
     */
    private int mTextSize;
    /**
     * 缩放参数
     */
    private int mImageScale;

    /**
     * 绘制时控制文本绘制的范围
     */
    private Rect mTextBound;
    /**
     * 绘制整体的范围
     */
    private Rect rect;
    /**
     * 画笔
     */
    private Paint mPaint;
    /**
     * 图像内容
     */
    private Bitmap mImage;
    /**
     * 控件宽度
     */
    private int mWidth;
    /**
     * 控件高度
     */
    private int mHeight;
    /**
     * 响应事件监听器
     */
    private CustomImageViewClickListener listener;

    /**
     * 构造方法
     *
     * @param context
     * @param attrs
     */
    public CustomImageView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    /**
     * 构造方法
     *
     * @param context
     */
    public CustomImageView(Context context) {
        this(context, null);
    }

    /**
     * 初始化所特有自定义类型
     *
     * @param context
     * @param attrs
     * @param defStyle
     */
    public CustomImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        this.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                if (listener != null) {
                    listener.onCustomImageViewClickListener(view);
                }
            }
        });
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomImageView, defStyle, 0);

        int n = a.getIndexCount();
        for (int i = 0; i < n; i++) {
            int attr = a.getIndex(i);
            switch (attr) {
                case R.styleable.CustomImageView_image:
                    mImage = BitmapFactory.decodeResource(getResources(), a.getResourceId(attr, 0));
                    break;
                case R.styleable.CustomImageView_imageScaleType:
                    mImageScale = a.getInt(attr, 0);
                    break;
                case R.styleable.CustomImageView_titleText:
                    mTitle = a.getString(attr);
                    break;
                case R.styleable.CustomImageView_titleTextColor:
                    mTextColor = a.getColor(attr, Color.BLACK);
                    break;
                case R.styleable.CustomImageView_titleTextSize:
                    mTextSize = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,
                            16, getResources().getDisplayMetrics()));
                    break;
            }
        }
        a.recycle();
        rect = new Rect();
        mPaint = new Paint();
        mTextBound = new Rect();
        mPaint.setTextSize(mTextSize);
        // 计算了描绘字体需要的范围
        mPaint.getTextBounds(mTitle, 0, mTitle.length(), mTextBound);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        /**
         * 设置宽度
         */
        int specMode = MeasureSpec.getMode(widthMeasureSpec);
        int specSize = MeasureSpec.getSize(widthMeasureSpec);

        if (specMode == MeasureSpec.EXACTLY) {// match_parent , accurate
            Log.e("xxx", "EXACTLY");
            mWidth = specSize;
        } else {
            // 由图片决定的宽
            int desireByImg = getPaddingLeft() + getPaddingRight() + mImage.getWidth();
            // 由字体决定的宽
            int desireByTitle = getPaddingLeft() + getPaddingRight() + mTextBound.width();

            if (specMode == MeasureSpec.AT_MOST) {// wrap_content
                int desire = Math.max(desireByImg, desireByTitle);
                mWidth = Math.min(desire, specSize);
                Log.e("xxx", "AT_MOST");
            }
        }

        /***
         * 设置高度
         */
        specMode = MeasureSpec.getMode(heightMeasureSpec);
        specSize = MeasureSpec.getSize(heightMeasureSpec);
        if (specMode == MeasureSpec.EXACTLY) {// match_parent , accurate
            mHeight = specSize;
        } else {
            int desire = getPaddingTop() + getPaddingBottom() + mImage.getHeight() + mTextBound.height();
            if (specMode == MeasureSpec.AT_MOST) {// wrap_content
                mHeight = Math.min(desire, specSize);
            }
        }
        setMeasuredDimension(mWidth, mHeight);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // super.onDraw(canvas);
        /**
         * 边框
         */
        mPaint.setStrokeWidth(4);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setColor(Color.CYAN);
        canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint);

        rect.left = getPaddingLeft();
        rect.right = mWidth - getPaddingRight();
        rect.top = getPaddingTop();
        rect.bottom = mHeight - getPaddingBottom();

        mPaint.setColor(mTextColor);
        mPaint.setStyle(Paint.Style.FILL);
        /**
         * 当前设置的宽度小于字体需要的宽度，将字体改为xxx...
         */
        if (mTextBound.width() > mWidth) {
            TextPaint paint = new TextPaint(mPaint);
            String msg = TextUtils.ellipsize(mTitle, paint, (float) mWidth - getPaddingLeft() - getPaddingRight(),
                    TextUtils.TruncateAt.END).toString();
            canvas.drawText(msg, getPaddingLeft(), mHeight - getPaddingBottom(), mPaint);

        } else {
            //正常情况，将字体居中
            canvas.drawText(mTitle, mWidth / 2 - mTextBound.width() * 1.0f / 2, mHeight - getPaddingBottom(), mPaint);
        }

        //取消使用掉的快
        rect.bottom -= mTextBound.height();

        if (mImageScale == IMAGE_SCALE_FITXY) {
            canvas.drawBitmap(mImage, null, rect, mPaint);
        } else {
            //计算居中的矩形范围
            rect.left = mWidth / 2 - mImage.getWidth() / 2;
            rect.right = mWidth / 2 + mImage.getWidth() / 2;
            rect.top = (mHeight - mTextBound.height()) / 2 - mImage.getHeight() / 2;
            rect.bottom = (mHeight - mTextBound.height()) / 2 + mImage.getHeight() / 2;

            canvas.drawBitmap(mImage, null, rect, mPaint);
        }
    }

    /**
     * 设置监听器
     *
     * @param listener
     */
    public void setListener(CustomImageViewClickListener listener) {
        this.listener = listener;
    }

    public interface CustomImageViewClickListener {
        void onCustomImageViewClickListener(View v);
    }
}

三、使用自定义控件

public class MainActivity extends AppCompatActivity implements CustomView.CustomListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ((CustomView) this.findViewById(R.id.custom1)).setCustomListener(this);
    }


    @Override
    public void onCuscomClick(View v, int custom_id) {
        switch (custom_id) {
            case 1:
                Toast.makeText(this, "你点我干嘛？！", Toast.LENGTH_LONG).show();
                break;
            default:
                break;
        }
    }

/**
 * 类说明：CustomImageView 展示页面
 * 增加：控件点击事件
 * 

 * 作者：vision
 * 时间：2016/7/15
 */
public class CustomImageViewActivity extends Activity implements CustomImageView.CustomImageViewClickListener {
    /**
     * 第一个控件
     */
    private CustomImageView pengyuyan1;
    /**
     * 第二个控件
     */
    private CustomImageView pengyuyan2;
    /**
     * 第三个控件
     */
    private CustomImageView pengyuyan3;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_custom_image_view);
        pengyuyan1 = (CustomImageView) findViewById(R.id.pengyuyan1);
        pengyuyan2 = (CustomImageView) findViewById(R.id.pengyuyan2);
        pengyuyan3 = (CustomImageView) findViewById(R.id.pengyuyan3);

        pengyuyan1.setListener(this);
        pengyuyan2.setListener(this);
        pengyuyan3.setListener(this);
    }

    @Override
    public void onCustomImageViewClickListener(View v) {
        switch (v.getId()) {
            case R.id.pengyuyan1:
                Toast.makeText(this, "帅哥彭于晏1", Toast.LENGTH_LONG).show();
                break;
            case R.id.pengyuyan2:
                Toast.makeText(this, "德艺双馨彭于晏2", Toast.LENGTH_LONG).show();

                break;
            case R.id.pengyuyan3:
                Toast.makeText(this, "超越自己彭于晏3", Toast.LENGTH_LONG).show();
                break;
        }
    }
}

四、相关类似功能的扩展
实现加载过程进度显示
TextView的背景修改自定义控件
效果如图：


这是源码哦

有些时候，我们自以为我们不配得到的，其实是我们错过的；而配不上我们的，还放肆的将我们辜负了。