从字符串(路径)创建VectorDrawable吗? [英] Create VectorDrawable from String (path)?
本文介绍了从字符串(路径)创建VectorDrawable吗?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
是否可以从API获取SVG路径字符串并动态创建 VectorDrawable ?
Is there a way to get SVG path string from the API and create VectorDrawable dynamically?
我已经尝试了好几个小时，但都没有成功.甚至，Internet上的所有(！)示例都说明了如何使用XML资源创建 VectorDrawable .
I have been trying to do this for hours without success. Even more, all (!) examples on the Internet explain creating VectorDrawable from XML resources.
就我而言，XML资源文件毫无意义，因为我试图从Internet API中获取SVG路径.
In my case, XML resource file is pointless as I am trying to fetch SVG path from the Internet API.
推荐答案
实际上不可能从XML文件而不是从资源中扩展可绘制对象，因为可绘制对象会尝试将 XmlPullParser 强制转换为 XmlResourceParser ，仅由私有类 XmlBlock.Parser 实现.即使该解析器也仅用于解析二进制XML文件.我尝试了所有可能的方法而没有反思，这是不可能的.
Inflating a drawable from a XML file instead of from resources is actually impossible, because the drawable will try to cast the XmlPullParser to XmlResourceParser which is only implemented by private class XmlBlock.Parser. Even that parser is only used for parsing binary XML files. I tried every possible way of doing this without reflection, it's impossible.
因此，我找到了关于二进制XML的文档，并了解了如何它们是由我拥有的一些经过编译的二进制XML矢量可绘制文件制成的.该文档的历史可以追溯到2011年，仍然有效，我想它很有可能会保持这种方式，因此将来的兼容性不是问题.
So I found documentation on binary XML files and learned how they were made, helped with some compiled binary XML vector drawable files I had. The documentation dates back to 2011 and is still valid, I guess it will most likely remain this way, so future compatibility isn't an issue.
以前的版本已针对1000多个路径进行了测试，没有问题.此处发布的新版本也应正常工作.(以前的版本可在答案历史记录中找到.)与直接从资源中加载可绘制对象相比，我发现平均有14毫秒左右的额外负载，并不明显.
A previous version was tested for more than a thousand paths, without problem. The new version posted here should work just as well. (Previous versions are available in the answer history) Compared with loading a drawable directly from resources, I found that there's an average of 14 microseconds or so of extra loading, not noticeable.
代码如下:
public class VectorDrawableCreator {
private static final byte[][] BIN_XML_STRINGS = {
"width".getBytes(),
"height".getBytes(),
"viewportWidth".getBytes(),
"viewportHeight".getBytes(),
"fillColor".getBytes(),
"pathData".getBytes(),
"path".getBytes(),
"vector".getBytes(),
"http://schemas.android.com/apk/res/android".getBytes()
};
private static final int[] BIN_XML_ATTRS = {
android.R.attr.height,
android.R.attr.width,
android.R.attr.viewportWidth,
android.R.attr.viewportHeight,
android.R.attr.fillColor,
android.R.attr.pathData
};
private static final short CHUNK_TYPE_XML = 0x0003;
private static final short CHUNK_TYPE_STR_POOL = 0x0001;
private static final short CHUNK_TYPE_START_TAG = 0x0102;
private static final short CHUNK_TYPE_END_TAG = 0x0103;
private static final short CHUNK_TYPE_RES_MAP = 0x0180;
private static final short VALUE_TYPE_DIMENSION = 0x0500;
private static final short VALUE_TYPE_STRING = 0x0300;
private static final short VALUE_TYPE_COLOR = 0x1D00;
private static final short VALUE_TYPE_FLOAT = 0x0400;
/**
* Create a vector drawable from a list of paths and colors
* @param width drawable width
* @param height drawable height
* @param viewportWidth vector image width
* @param viewportHeight vector image height
* @param paths list of path data and colors
* @return the vector drawable or null it couldn't be created.
*/
public static Drawable getVectorDrawable(@NonNull Context context,
int width, int height,
float viewportWidth, float viewportHeight,
List<PathData> paths) {
byte[] binXml = createBinaryDrawableXml(width, height, viewportWidth, viewportHeight, paths);
try {
// Get the binary XML parser (XmlBlock.Parser) and use it to create the drawable
// This is the equivalent of what AssetManager#getXml() does
@SuppressLint("PrivateApi")
Class<?> xmlBlock = Class.forName("android.content.res.XmlBlock");
Constructor xmlBlockConstr = xmlBlock.getConstructor(byte[].class);
Method xmlParserNew = xmlBlock.getDeclaredMethod("newParser");
xmlBlockConstr.setAccessible(true);
xmlParserNew.setAccessible(true);
XmlPullParser parser = (XmlPullParser) xmlParserNew.invoke(
xmlBlockConstr.newInstance((Object) binXml));
if (Build.VERSION.SDK_INT >= 24) {
return Drawable.createFromXml(context.getResources(), parser);
} else {
// Before API 24, vector drawables aren't rendered correctly without compat lib
final AttributeSet attrs = Xml.asAttributeSet(parser);
int type = parser.next();
while (type != XmlPullParser.START_TAG) {
type = parser.next();
}
return VectorDrawableCompat.createFromXmlInner(context.getResources(), parser, attrs, null);
}
} catch (Exception e) {
Log.e(VectorDrawableCreator.class.getSimpleName(), "Vector creation failed", e);
}
return null;
}
private static byte[] createBinaryDrawableXml(int width, int height,
float viewportWidth, float viewportHeight,
List<PathData> paths) {
List<byte[]> stringPool = new ArrayList<>(Arrays.asList(BIN_XML_STRINGS));
for (PathData path : paths) {
stringPool.add(path.data);
}
ByteBuffer bb = ByteBuffer.allocate(8192); // Capacity might have to be greater.
bb.order(ByteOrder.LITTLE_ENDIAN);
int posBefore;
// ==== XML chunk ====
// https://justanapplication.wordpress.com/2011/09/22/android-internals-binary-xml-part-two-the-xml-chunk/
bb.putShort(CHUNK_TYPE_XML); // Type
bb.putShort((short) 8); // Header size
int xmlSizePos = bb.position();
bb.position(bb.position() + 4);
// ==== String pool chunk ====
// https://justanapplication.wordpress.com/2011/09/15/android-internals-resources-part-four-the-stringpool-chunk/
int spStartPos = bb.position();
bb.putShort(CHUNK_TYPE_STR_POOL); // Type
bb.putShort((short) 28); // Header size
int spSizePos = bb.position();
bb.position(bb.position() + 4);
bb.putInt(stringPool.size()); // String count
bb.putInt(0); // Style count
bb.putInt(1 << 8); // Flags set: encoding is UTF-8
int spStringsStartPos = bb.position();
bb.position(bb.position() + 4);
bb.putInt(0); // Styles start
// String offsets
int offset = 0;
for (byte[] str : stringPool) {
bb.putInt(offset);
offset += str.length + (str.length > 127 ? 5 : 3);
}
posBefore = bb.position();
bb.putInt(spStringsStartPos, bb.position() - spStartPos);
bb.position(posBefore);
// String pool
for (byte[] str : stringPool) {
if (str.length > 127) {
byte high = (byte) ((str.length & 0xFF00 | 0x8000) >>> 8);
byte low = (byte) (str.length & 0xFF);
bb.put(high);
bb.put(low);
bb.put(high);
bb.put(low);
} else {
byte len = (byte) str.length;
bb.put(len);
bb.put(len);
}
bb.put(str);
bb.put((byte) 0);
}
if (bb.position() % 4 != 0) {
// Padding to align on 32-bit
bb.put(new byte[4 - (bb.position() % 4)]);
}
// Write string pool chunk size
posBefore = bb.position();
bb.putInt(spSizePos, bb.position() - spStartPos);
bb.position(posBefore);
// ==== Resource map chunk ====
// https://justanapplication.wordpress.com/2011/09/23/android-internals-binary-xml-part-four-the-xml-resource-map-chunk/
bb.putShort(CHUNK_TYPE_RES_MAP); // Type
bb.putShort((short) 8); // Header size
bb.putInt(8 + BIN_XML_ATTRS.length * 4); // Chunk size
for (int attr : BIN_XML_ATTRS) {
bb.putInt(attr);
}
// ==== Vector start tag ====
int vstStartPos = bb.position();
int vstSizePos = putStartTag(bb, 7, 4);
// Attributes
// android:width="24dp", value type: dimension (dp)
putAttribute(bb, 0, -1, VALUE_TYPE_DIMENSION, (width << 8) + 1);
// android:height="24dp", value type: dimension (dp)
putAttribute(bb, 1, -1, VALUE_TYPE_DIMENSION, (height << 8) + 1);
// android:viewportWidth="24", value type: float
putAttribute(bb, 2, -1, VALUE_TYPE_FLOAT, Float.floatToRawIntBits(viewportWidth));
// android:viewportHeight="24", value type: float
putAttribute(bb, 3, -1, VALUE_TYPE_FLOAT, Float.floatToRawIntBits(viewportHeight));
// Write vector start tag chunk size
posBefore = bb.position();
bb.putInt(vstSizePos, bb.position() - vstStartPos);
bb.position(posBefore);
for (int i = 0; i < paths.size(); i++) {
// ==== Path start tag ====
int pstStartPos = bb.position();
int pstSizePos = putStartTag(bb, 6, 2);
// android:fillColor="#aarrggbb", value type: #rgb.
putAttribute(bb, 4, -1, VALUE_TYPE_COLOR, paths.get(i).color);
// android:pathData="...", value type: string
putAttribute(bb, 5, 9 + i, VALUE_TYPE_STRING, 9 + i);
// Write path start tag chunk size
posBefore = bb.position();
bb.putInt(pstSizePos, bb.position() - pstStartPos);
bb.position(posBefore);
// ==== Path end tag ====
putEndTag(bb, 6);
}
// ==== Vector end tag ====
putEndTag(bb, 7);
// Write XML chunk size
posBefore = bb.position();
bb.putInt(xmlSizePos, bb.position());
bb.position(posBefore);
// Return binary XML byte array
byte[] binXml = new byte[bb.position()];
bb.rewind();
bb.get(binXml);
return binXml;
}
private static int putStartTag(ByteBuffer bb, int name, int attributeCount) {
// https://justanapplication.wordpress.com/2011/09/25/android-internals-binary-xml-part-six-the-xml-start-element-chunk/
bb.putShort(CHUNK_TYPE_START_TAG);
bb.putShort((short) 16); // Header size
int sizePos = bb.position();
bb.putInt(0); // Size, to be set later
bb.putInt(0); // Line number: None
bb.putInt(-1); // Comment: None
bb.putInt(-1); // Namespace: None
bb.putInt(name);
bb.putShort((short) 0x14); // Attributes start offset
bb.putShort((short) 0x14); // Attributes size
bb.putShort((short) attributeCount); // Attribute count
bb.putShort((short) 0); // ID attr: none
bb.putShort((short) 0); // Class attr: none
bb.putShort((short) 0); // Style attr: none
return sizePos;
}
private static void putEndTag(ByteBuffer bb, int name) {
// https://justanapplication.wordpress.com/2011/09/26/android-internals-binary-xml-part-seven-the-xml-end-element-chunk/
bb.putShort(CHUNK_TYPE_END_TAG);
bb.putShort((short) 16); // Header size
bb.putInt(24); // Chunk size
bb.putInt(0); // Line number: none
bb.putInt(-1); // Comment: none
bb.putInt(-1); // Namespace: none
bb.putInt(name); // Name: vector
}
private static void putAttribute(ByteBuffer bb, int name,
int rawValue, short valueType, int valueData) {
// https://justanapplication.wordpress.com/2011/09/19/android-internals-resources-part-eight-resource-entries-and-values/#struct_Res_value
bb.putInt(8); // Namespace index in string pool (always the android namespace)
bb.putInt(name);
bb.putInt(rawValue);
bb.putShort((short) 0x08); // Value size
bb.putShort(valueType);
bb.putInt(valueData);
}
public static class PathData {
public byte[] data;
public int color;
public PathData(byte[] data, int color) {
this.data = data;
this.color = color;
}
public PathData(String data, int color) {
this(data.getBytes(StandardCharsets.UTF_8), color);
}
}
}
对 getVectorDrawable 的调用从路径列表中返回 VectorDrawable .可绘制对象可以包含具有不同颜色的多个路径.还有可绘制和视口大小的参数.
A call to getVectorDrawable returns a VectorDrawable from a list of paths. The drawable can contain multiple paths with different colors. There are also parameters for the drawable and viewport size.
这是一个例子:
List<PathData> pathList = Arrays.asList(new PathData("M128.09 5.02a110.08 110.08 0 0 0-110 110h220a109.89 109.89 0 0 0-110-110z", Color.parseColor("#7cb342")),
new PathData("M128.09 115.02h-110a110.08 110.08 0 0 0 110 110 110.08 110.08 0 0 0 110-110z", Color.parseColor("#8bc34a")),
new PathData("M207.4 115.2v-.18h-5.1l-61.43-61.43h-25.48v20.6h-6.5a11.57 11.57 0 0 0-11.53 11.53v26.09h.11c-.11.9.5 2 1.7 3.32.12.08.12.08.12.2l3.96 4-46.11 79.91c5.33 4.5 11.04 8.4 17 11.8a109.81 109.81 0 0 0 108.04 0 110.04 110.04 0 0 0 51.52-64.65c.38-1.28.68-2.57 1.1-3.78z", Color.parseColor("#30000000")),
new PathData("M216.28 230.24a6.27 6.27 0 0 0-.9-2.8l-31.99-55.57-10.58-18.48-19.85-34.21-15.08 15.12 18.6 32.28 10.2 17.73 30.92 53.37a5.6 5.6 0 0 0 1.97 2.12l15.42 10.5c.6.39 1.29.39 1.9.08.6-.37.9-.98.9-1.7z", Color.parseColor("#e1e1e1")),
new PathData("M186.98 115.02a58.9 58.9 0 0 1-30.5 51.6 58.4 58.4 0 0 1-56.7 0l18.6-32.28-15.13-15.12-62.48 108.22c-.5.9-.8 1.78-.9 2.8l-1.4 18.6c-.12.71.3 1.28.9 1.7.6.37 1.29.3 1.9-.12l15.41-10.4a7.87 7.87 0 0 0 1.97-2.07l30.92-53.53a78.74 78.74 0 0 0 77.23 0 76.65 76.65 0 0 0 16.6-12.4 79.3 79.3 0 0 0 24.07-56.89z", Color.parseColor("#f1f1f1")),
new PathData("M147.3 74.12h-6.43v-20.6h-25.48v20.6h-6.5a11.57 11.57 0 0 0-11.53 11.5v26.07h.11c-.11 1.02.5 2.12 1.82 3.4l23.05 23.14a8.3 8.3 0 0 0 5.75 2.38v-.07l.07.07c2.12 0 4.2-.75 5.71-2.38l23.1-23.1c1.32-1.32 1.81-2.53 1.81-3.4h.12V85.7a11.68 11.68 0 0 0-11.6-11.6zm-19.14 40.9h-.07a15.4 15.4 0 0 1 0-30.8v-.2l.07.2a15.46 15.46 0 0 1 15.31 15.38 15.46 15.46 0 0 1-15.3 15.42z", Color.parseColor("#646464")));
这篇关于从字符串(路径)创建VectorDrawable吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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