Android:编译9补丁文件以在可绘制文件夹之外使用？

Question

我需要从drawable文件夹之外加载9-patch文件。例如，这是为了让我的应用程序可以从服务器下载新的皮肤。我发现存储在可绘制文件夹中的9补丁图像是在制作.apk时编译的。从assets文件夹读取的完全相同的文件没有9-patch块。因此，生成.apk的操作是在可绘制文件夹中编译源9-patch文件，而不是在资产目录中。

我如何自己编译一个包含9个补丁的文件，以便可以将其安装在资源目录中？有没有一个(批处理)工具可以将源代码转换为带有9-patch块的编译版本？我真的非常希望不必使用Eclipse来构建一个.apk，然后在可能的情况下将其解压到编译后的9-patch文件中。

现在，我只希望能够读取资源目录(例如，每个皮肤都有一个子目录)，以保持简单。下一步是编译源映像以添加到9-patch块中。在那之后，我会担心动态下载到/data文件夹-如果我不能编译9-patch文件，那么添加服务器端的工作就没有什么意义了。

Answer 1

没有简单的方法可以做到这一点afaik。9-patch编译是由aapt完成的，并且非常简单:它丢弃了黑色边框，并将其内容编码到PNG块中。对于你来说，编写一个做类似事情的工具是相当微不足道的。请注意，您甚至不需要使用相同的格式。如果您查看文档中的各种NinePatch API，您将看到您可以提交自己的“块”(它对拉伸区域和填充进行编码)。块byte[]数组的结构如下所示：

/**
 * This chunk specifies how to split an image into segments for
 * scaling.
 *
 * There are J horizontal and K vertical segments.  These segments divide
 * the image into J*K regions as follows (where J=4 and K=3):
 *
 *      F0   S0    F1     S1
 *   +-----+----+------+-------+
 * S2|  0  |  1 |  2   |   3   |
 *   +-----+----+------+-------+
 *   |     |    |      |       |
 *   |     |    |      |       |
 * F2|  4  |  5 |  6   |   7   |
 *   |     |    |      |       |
 *   |     |    |      |       |
 *   +-----+----+------+-------+
 * S3|  8  |  9 |  10  |   11  |
 *   +-----+----+------+-------+
 *
 * Each horizontal and vertical segment is considered to by either
 * stretchable (marked by the Sx labels) or fixed (marked by the Fy
 * labels), in the horizontal or vertical axis, respectively. In the
 * above example, the first is horizontal segment (F0) is fixed, the
 * next is stretchable and then they continue to alternate. Note that
 * the segment list for each axis can begin or end with a stretchable
 * or fixed segment.
 *
 * The relative sizes of the stretchy segments indicates the relative
 * amount of stretchiness of the regions bordered by the segments.  For
 * example, regions 3, 7 and 11 above will take up more horizontal space
 * than regions 1, 5 and 9 since the horizontal segment associated with
 * the first set of regions is larger than the other set of regions.  The
 * ratios of the amount of horizontal (or vertical) space taken by any
 * two stretchable slices is exactly the ratio of their corresponding
 * segment lengths.
 *
 * xDivs and yDivs point to arrays of horizontal and vertical pixel
 * indices.  The first pair of Divs (in either array) indicate the
 * starting and ending points of the first stretchable segment in that
 * axis. The next pair specifies the next stretchable segment, etc. So
 * in the above example xDiv[0] and xDiv[1] specify the horizontal
 * coordinates for the regions labeled 1, 5 and 9.  xDiv[2] and
 * xDiv[3] specify the coordinates for regions 3, 7 and 11. Note that
 * the leftmost slices always start at x=0 and the rightmost slices
 * always end at the end of the image. So, for example, the regions 0,
 * 4 and 8 (which are fixed along the X axis) start at x value 0 and
 * go to xDiv[0] and slices 2, 6 and 10 start at xDiv[1] and end at
 * xDiv[2].
 *
 * The array pointed to by the colors field lists contains hints for
 * each of the regions.  They are ordered according left-to-right and
 * top-to-bottom as indicated above. For each segment that is a solid
 * color the array entry will contain that color value; otherwise it
 * will contain NO_COLOR.  Segments that are completely transparent
 * will always have the value TRANSPARENT_COLOR.
 *
 * The PNG chunk type is "npTc".
 */
struct Res_png_9patch
{
    Res_png_9patch() : wasDeserialized(false), xDivs(NULL),
                       yDivs(NULL), colors(NULL) { }

    int8_t wasDeserialized;
    int8_t numXDivs;
    int8_t numYDivs;
    int8_t numColors;

    // These tell where the next section of a patch starts.
    // For example, the first patch includes the pixels from
    // 0 to xDivs[0]-1 and the second patch includes the pixels
    // from xDivs[0] to xDivs[1]-1.
    // Note: allocation/free of these pointers is left to the caller.
    int32_t* xDivs;
    int32_t* yDivs;

    int32_t paddingLeft, paddingRight;
    int32_t paddingTop, paddingBottom;

    enum {
        // The 9 patch segment is not a solid color.
        NO_COLOR = 0x00000001,

        // The 9 patch segment is completely transparent.
        TRANSPARENT_COLOR = 0x00000000
    };
    // Note: allocation/free of this pointer is left to the caller.
    uint32_t* colors;

    // Convert data from device representation to PNG file representation.
    void deviceToFile();
    // Convert data from PNG file representation to device representation.
    void fileToDevice();
    // Serialize/Marshall the patch data into a newly malloc-ed block
    void* serialize();
    // Serialize/Marshall the patch data
    void serialize(void* outData);
    // Deserialize/Unmarshall the patch data
    static Res_png_9patch* deserialize(const void* data);
    // Compute the size of the serialized data structure
    size_t serializedSize();
};

Answer 2

这是一个适用于我的情况的变通方法。

我的应用程序中有默认的9补丁图像，我将其用作消息气泡。我想创建可下载的themes，它可以改变气泡和其他东西，如字体颜色等。

可绘制文件夹中包含的*.9.png图像是默认图像，它们包含图像周围的黑色像素：

​

default_outgoing.9.png

“自定义”/themed气泡具有完全相同的尺寸，放置位置略有变化，仍然使用与默认区域相同的“块”区域，但这些气泡在文件名中不包括黑色像素或.9：

​

pink_round_outgoing.png

那么，如何在自定义版本工作的同时仍然保持良好的外观呢？下面是一些代码，它获取自定义图像，从默认的9补丁图像中获取一些值，并将它们应用于自定义位图：

//Get the custom replacement image
Bitmap bitmap = BitmapFactory.decodeFile(folderpath + File.separator + "pink_round_outgoing.png");

//Get padding from the default 9-patch drawable
Drawable existingDrawable = ContextCompat.getDrawable(this, R.drawable.default_outgoing);
Rect padding = new Rect();
if (existingDrawable != null) {
    existingDrawable.getPadding(padding);
}

//Get 9-patch chunk from the default 9-patch drawable
Bitmap existingBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.default_outgoing);
byte[] chunk = existingBitmap.getNinePatchChunk();

//Finally create your custom 9-Patch drawable and set it to background
NinePatchDrawable d = new NinePatchDrawable(getResources(), bitmap, chunk, padding, null);
view.setBackground(d);