PixelFormat（像素格式）以及view的高度getX（），getRawX（）以及Path所用

慢慢看你们不会领悟的

public class PixelFormat
{
    /* these constants need to match those in hardware/hardware.h */

    public static final int UNKNOWN     = 0;

    /** System chooses a format that supports translucency (many alpha bits) */
    public static final int TRANSLUCENT = -3;

    /**
     * System chooses a format that supports transparency
     * (at least 1 alpha bit)
     */
    public static final int TRANSPARENT = -2;

    /** System chooses an opaque format (no alpha bits required) */
    public static final int OPAQUE      = -1;

    public static final int RGBA_8888   = 1;
    public static final int RGBX_8888   = 2;
    public static final int RGB_888     = 3;
    public static final int RGB_565     = 4;

    @Deprecated
    public static final int RGBA_5551   = 6;
    @Deprecated
    public static final int RGBA_4444   = 7;
    @Deprecated
    public static final int A_8         = 8;
    @Deprecated
    public static final int L_8         = 9;
    @Deprecated
    public static final int LA_88       = 0xA;
    @Deprecated
    public static final int RGB_332     = 0xB;


    /**
     * @deprecated use {@link android.graphics.ImageFormat#NV16
     * ImageFormat.NV16} instead.
     */
    @Deprecated
    public static final int YCbCr_422_SP= 0x10;

    /**
     * @deprecated use {@link android.graphics.ImageFormat#NV21
     * ImageFormat.NV21} instead.
     */
    @Deprecated
    public static final int YCbCr_420_SP= 0x11;

    /**
     * @deprecated use {@link android.graphics.ImageFormat#YUY2
     * ImageFormat.YUY2} instead.
     */
    @Deprecated
    public static final int YCbCr_422_I = 0x14;

    /**
     * @deprecated use {@link android.graphics.ImageFormat#JPEG
     * ImageFormat.JPEG} instead.
     */
    @Deprecated
    public static final int JPEG        = 0x100;

    public static void getPixelFormatInfo(int format, PixelFormat info) {
        switch (format) {
            case RGBA_8888:
            case RGBX_8888:
                info.bitsPerPixel = 32;
                info.bytesPerPixel = 4;
                break;
            case RGB_888:
                info.bitsPerPixel = 24;
                info.bytesPerPixel = 3;
                break;
            case RGB_565:
            case RGBA_5551:
            case RGBA_4444:
            case LA_88:
                info.bitsPerPixel = 16;
                info.bytesPerPixel = 2;
                break;
            case A_8:
            case L_8:
            case RGB_332:
                info.bitsPerPixel = 8;
                info.bytesPerPixel = 1;
                break;
            case YCbCr_422_SP:
            case YCbCr_422_I:
                info.bitsPerPixel = 16;
                info.bytesPerPixel = 1;
                break;
            case YCbCr_420_SP:
                info.bitsPerPixel = 12;
                info.bytesPerPixel = 1;
                break;
            default:
                throw new IllegalArgumentException("unknown pixel format " + format);
        }
    }

    public static boolean formatHasAlpha(int format) {
        switch (format) {
            case PixelFormat.A_8:
            case PixelFormat.LA_88:
            case PixelFormat.RGBA_4444:
            case PixelFormat.RGBA_5551:
            case PixelFormat.RGBA_8888:
            case PixelFormat.TRANSLUCENT:
            case PixelFormat.TRANSPARENT:
                return true;
        }
        return false;
    }

    public int  bytesPerPixel;
    public int  bitsPerPixel;

    /**
     * Determine whether or not this is a public-visible and non-deprecated {@code format}.
     *
     * <p>In particular, {@code @hide} formats will return {@code false}.</p>
     *
     * <p>Any other indirect formats (such as {@code TRANSPARENT} or {@code TRANSLUCENT})
     * will return {@code false}.</p>
     *
     * @param format an integer format
     * @return a boolean
     *
     * @hide
     */
    public static boolean isPublicFormat(int format) {
        switch (format) {
            case RGBA_8888:
            case RGBX_8888:
            case RGB_888:
            case RGB_565:
                return true;
        }

        return false;
    }
}

优先考虑线性布局，再使用相对布局，优先考虑padding，在使用margin

做个笔记

getRawX（）是相对于手机屏幕
getX（）相对于自身左上角
getTop（）相对于父空间

Path类中的几个方法用法

public void lineTo (float x, float y)
Added in API level 1

Add a line from the last point to the specified point (x,y). If no moveTo() call has been made for this contour, the first point is automatically set to (0,0).
Parameters
x   The x-coordinate of the end of a line
y   The y-coordinate of the end of a line
public void moveTo (float x, float y)
Added in API level 1

Set the beginning of the next contour to the point (x,y).
Parameters
x   The x-coordinate of the start of a new contour
y   The y-coordinate of the start of a new contour 


 public void quadTo (float x1, float y1, float x2, float y2)
Added in API level 1

Add a quadratic bezier from the last point, approaching control point (x1,y1), and ending at (x2,y2). If no moveTo() call has been made for this contour, the first point is automatically set to (0,0).
Parameters
x1  The x-coordinate of the control point on a quadratic curve
y1  The y-coordinate of the control point on a quadratic curve
x2  The x-coordinate of the end point on a quadratic curve
y2  The y-coordinate of the end point on a quadratic curve