【Android UI】绘制圆角矩形进度条 ① ( 像素值转化 dp -＞ px | Paint 标志位设置 | Paint 画笔线帽样式设置 | Paint 画笔线段连接处样式设置 )

    /**
     * 将 dp 屏幕像素 值转为 px 真实像素值, 目的是使用 dp 为单位在手机中显示相同的效果
     * @param dp
     * @return
     */
    public float dp2px(float dp){
        return TypedValue.applyDimension(
                TypedValue.COMPLEX_UNIT_DIP,
                dp,
                getResources().getDisplayMetrics());
    }

mReachedPaint.setStrokeWidth(dp2px(10));

        // 抗锯齿 : Paint.ANTI_ALIAS_FLAG
        // 闪烁时启动抖动 : Paint.DITHER_FLAG
        mReachedPaint=new Paint(Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG);

    /**
     * Paint flag that enables antialiasing when drawing.
     *
     * <p>Enabling this flag will cause all draw operations that support
     * antialiasing to use it.</p>
     *
     * @see #Paint(int)
     * @see #setFlags(int)
     */
    public static final int ANTI_ALIAS_FLAG     = 0x01;
    /**
     * Paint flag that enables bilinear sampling on scaled bitmaps.
     *
     * <p>If cleared, scaled bitmaps will be drawn with nearest neighbor
     * sampling, likely resulting in artifacts. This should generally be on
     * when drawing bitmaps, unless performance-bound (rendering to software
     * canvas) or preferring pixelation artifacts to blurriness when scaling
     * significantly.</p>
     *
     * <p>If bitmaps are scaled for device density at creation time (as
     * resource bitmaps often are) the filtering will already have been
     * done.</p>
     *
     * <p>On devices running {@link Build.VERSION_CODES#O} and below, hardware
     * accelerated drawing always uses bilinear sampling on scaled bitmaps,
     * regardless of this flag. On devices running {@link Build.VERSION_CODES#Q}
     * and above, this flag defaults to being set on a new {@code Paint}. It can
     * be cleared with {@link #setFlags} or {@link #setFilterBitmap}.</p>
     *
     * @see #Paint()
     * @see #Paint(int)
     * @see #setFlags(int)
     */
    public static final int FILTER_BITMAP_FLAG  = 0x02;
    /**
     * Paint flag that enables dithering when blitting.
     *
     * <p>Enabling this flag applies a dither to any blit operation where the
     * target's colour space is more constrained than the source.
     *
     * @see #Paint(int)
     * @see #setFlags(int)
     */
    public static final int DITHER_FLAG         = 0x04;
    /**
     * Paint flag that applies an underline decoration to drawn text.
     *
     * @see #Paint(int)
     * @see #setFlags(int)
     */
    public static final int UNDERLINE_TEXT_FLAG = 0x08;
    /**
     * Paint flag that applies a strike-through decoration to drawn text.
     *
     * @see #Paint(int)
     * @see #setFlags(int)
     */
    public static final int STRIKE_THRU_TEXT_FLAG = 0x10;
    /**
     * Paint flag that applies a synthetic bolding effect to drawn text.
     *
     * <p>Enabling this flag will cause text draw operations to apply a
     * simulated bold effect when drawing a {@link Typeface} that is not
     * already bold.</p>
     *
     * @see #Paint(int)
     * @see #setFlags(int)
     */
    public static final int FAKE_BOLD_TEXT_FLAG = 0x20;
    /**
     * Paint flag that enables smooth linear scaling of text.
     *
     * <p>Enabling this flag does not actually scale text, but rather adjusts
     * text draw operations to deal gracefully with smooth adjustment of scale.
     * When this flag is enabled, font hinting is disabled to prevent shape
     * deformation between scale factors, and glyph caching is disabled due to
     * the large number of glyph images that will be generated.</p>
     *
     * <p>{@link #SUBPIXEL_TEXT_FLAG} should be used in conjunction with this
     * flag to prevent glyph positions from snapping to whole pixel values as
     * scale factor is adjusted.</p>
     *
     * @see #Paint(int)
     * @see #setFlags(int)
     */
    public static final int LINEAR_TEXT_FLAG    = 0x40;
    /**
     * Paint flag that enables subpixel positioning of text.
     *
     * <p>Enabling this flag causes glyph advances to be computed with subpixel
     * accuracy.</p>
     *
     * <p>This can be used with {@link #LINEAR_TEXT_FLAG} to prevent text from
     * jittering during smooth scale transitions.</p>
     *
     * @see #Paint(int)
     * @see #setFlags(int)
     */
    public static final int SUBPIXEL_TEXT_FLAG  = 0x80;
    /** Legacy Paint flag, no longer used. */
    public static final int DEV_KERN_TEXT_FLAG  = 0x100;
    /** @hide bit mask for the flag enabling subpixel glyph rendering for text */
    public static final int LCD_RENDER_TEXT_FLAG = 0x200;
    /**
     * Paint flag that enables the use of bitmap fonts when drawing text.
     *
     * <p>Disabling this flag will prevent text draw operations from using
     * embedded bitmap strikes in fonts, causing fonts with both scalable
     * outlines and bitmap strikes to draw only the scalable outlines, and
     * fonts with only bitmap strikes to not draw at all.</p>
     *
     * @see #Paint(int)
     * @see #setFlags(int)
     */
    public static final int EMBEDDED_BITMAP_TEXT_FLAG = 0x400;
    /** @hide bit mask for the flag forcing freetype's autohinter on for text */
    public static final int AUTO_HINTING_TEXT_FLAG = 0x800;
    /** @hide bit mask for the flag enabling vertical rendering for text */
    public static final int VERTICAL_TEXT_FLAG = 0x1000;

    // These flags are always set on a new/reset paint, even if flags 0 is passed.
    static final int HIDDEN_DEFAULT_PAINT_FLAGS = DEV_KERN_TEXT_FLAG | EMBEDDED_BITMAP_TEXT_FLAG
            | FILTER_BITMAP_FLAG;

mReachedPaint.setStrokeCap(Paint.Cap.ROUND);

    /**
     * The Cap specifies the treatment for the beginning and ending of
     * stroked lines and paths. The default is BUTT.
     */
    public enum Cap {
        /**
         * The stroke ends with the path, and does not project beyond it.
         */
        BUTT    (0),
        /**
         * The stroke projects out as a semicircle, with the center at the
         * end of the path.
         */
        ROUND   (1),
        /**
         * The stroke projects out as a square, with the center at the end
         * of the path.
         */
        SQUARE  (2);

        private Cap(int nativeInt) {
            this.nativeInt = nativeInt;
        }
        final int nativeInt;
    }

mReachedPaint.setStrokeJoin(Paint.Join.ROUND);

    /**
     * The Join specifies the treatment where lines and curve segments
     * join on a stroked path. The default is MITER.
     */
    public enum Join {
        /**
         * The outer edges of a join meet at a sharp angle
         */
        MITER   (0),
        /**
         * The outer edges of a join meet in a circular arc.
         */
        ROUND   (1),
        /**
         * The outer edges of a join meet with a straight line
         */
        BEVEL   (2);

        private Join(int nativeInt) {
            this.nativeInt = nativeInt;
        }
        final int nativeInt;
    }