SVG-Android库 深入浅出 解析篇

• 入口
• 通过解析得到SVG
• 将得到的SVG渲染到Picture\Canvas上

1. 入口

1.getFromInputStream(InputStream) : SVG 2.getFromString(String) : SVG 3.getFromResource(Resources, int) : SVG 4.getFromAsset(AssetManager, String) : SVG

// *************** com.caverock.androidsvg.SVG ***************

/**
* Read and parse an SVG from the given {@code InputStream}.
*
* @param is the input stream from which to read the file.
* @return an SVG instance on which you can call one of the render methods.
* @throws SVGParseException if there is an error parsing the document.
*/
getFromInputStream(InputStream) : SVG

/**
* Read and parse an SVG from the given {@code String}.
*
* @param svg the String instance containing the SVG document.
* @return an SVG instance on which you can call one of the render methods.
* @throws SVGParseException if there is an error parsing the document.
*/
getFromString(String) : SVG

/**
* Read and parse an SVG from the given resource location.
*
* @param context the Android context of the resource.
* @param resourceId the resource identifier of the SVG document.
* @return an SVG instance on which you can call one of the render methods.
* @throws SVGParseException if there is an error parsing the document.
*/
getFromResource(Context, int) : SVG

/**
* Read and parse an SVG from the given resource location.
*
* @param resources the set of Resources in which to locate the file.
* @param resourceId the resource identifier of the SVG document.
* @return an SVG instance on which you can call one of the render methods.
* @throws SVGParseException if there is an error parsing the document.
*/
getFromResource(Resources, int) : SVG

/**
* Read and parse an SVG from the assets folder.
*
* @param assetManager the AssetManager instance to use when reading the file.
* @param filename the filename of the SVG document within assets.
* @return an SVG instance on which you can call one of the render methods.
* @throws SVGParseException if there is an error parsing the document.
* @throws IOException if there is some IO error while reading the file.
*/
getFromAsset(AssetManager, String) : SVG

2. 通过解析得到SVG

2.1 输入

xml InputStream 或 zip InputStream

2.2 输出

SVG

2.3 XML解析器

SAX

2.4 解析引擎

• SVGParser // 主要引擎 继承自 com.xml.sax.ext.DefaultHandler2
• CCSSVGParser //主要用于解析CSS样式

2.5 解析工具

• NumberParser //解析SVG/Style中 ‘number’元素内容（速度快于系统）
• IntegerParser //解析SVG/Style中 ‘integer’元素或者哈希（速度快于系统）
• PreserveAspectRatio //在这里用于存储位置与缩放

2.6 解析流程

startDocument

startElement

characters

endElement

endDocument

2.7 层级管理

startDocument

svgDocument = new SVG();

startElement

......
SVG.SVGObject obj = new SVG.SVGObject();
......
if (currentElement == null) {
	svgDocument.setRootElement(obj);
} else {
	currentElement.addChild(obj);
}
currentElement = obj;

characters

......
if (currentElement instanceof SVG.TextContainer) {
	// The SAX parser can pass us several text nodes in a row. If this happens, we
	// want to collapse them all into one SVG.TextSequence node				
	SVG.SvgConditionalContainer parent = (SVG.SvgConditionalContainer) currentElement;
	int numOlderSiblings = parent.children.size();
	SVG.SvgObject previousSibling = (numOlderSiblings == 0) ? null : parent.children.get(numOlderSiblings - 1);
	if (previousSibling instanceof SVG.TextSequence) {
		// Last sibling was a TextSequence also, so merge them.
		((SVG.TextSequence) previousSibling).text += new String(ch, start, length);
	} else {
		// Add a new TextSequence to the child node list
		((SVG.SvgConditionalContainer) currentElement).addChild(new SVG.TextSequence(new String(ch, start, length)));
	}
}

endElement

......
currentElement = ((SvgObject) currentElement).parent;

endDocument

......

3. 将得到的SVG渲染到Picture\Canvas上

3.1 渲染入口

1.renderToPicture() : Picture 2.renderToPicture(int, int) : Picture 3.renderViewToPicture(String, int, int) : Picture 4.renderToCanvas(Canvas) : void 5.renderToCanvas(Canvas, RectF) : void 6.renderViewToCanvas(String, Canvas) : void 7.renderViewToCanvas(String, Canvas, RectF) : void

/**
  * Renders this SVG document to a Picture object.
  * <p>
  * An attempt will be made to determine a suitable initial viewport from the contents of the SVG file.
  * If an appropriate viewport can't be determined, a default viewport of 512x512 will be used.
  *
  * @return a Picture object suitable for later rendering using {@code Canvas.drawPicture()}
  */
renderToPicture() : Picture

/**
  * Renders this SVG document to a Picture object.
  *
  * @param widthInPixels the width of the initial viewport
  * @param heightInPixels the height of the initial viewport
  * @return a Picture object suitable for later rendering using {@code Canvas.darwPicture()}
  */
renderToPicture(int, int) : Picture

/**
  * Renders this SVG document to a Picture object using the specified view defined in the document.
  * <p>
  * A View is an special element in a SVG document that describes a rectangular area in the document.
  * Calling this method with a {@code viewId} will result in the specified view being positioned and scaled
  * to the viewport.  In other words, use {@link #renderToPicture()} to render the whole document, or use this
  * method instead to render just a part of it.
  *
  * @param viewId the id of a view element in the document that defines which section of the document is to be visible.
  * @param widthInPixels the width of the initial viewport
  * @param heightInPixels the height of the initial viewport
  * @return a Picture object suitable for later rendering using {@code Canvas.drawPicture()}, or null if the viewId was not found.
  */
renderViewToPicture(String, int, int) : Picture

/**
  * Renders this SVG document to a Canvas object.  The full width and height of the canvas
  * will be used as the viewport into which the document will be rendered.
  *
  * @param canvas the canvas to which the document should be rendered.
  */
renderToCanvas(Canvas) : void

 /**
  * Renders this SVG document to a Canvas object.
  *
  * @param canvas the canvas to which the document should be rendered.
  * @param viewPort the bounds of the area on the canvas you want the SVG rendered, or null for the whole canvas.
  */
renderToCanvas(Canvas, RectF) : void

/**
  * Renders this SVG document to a Canvas using the specified view defined in the document.
  * <p>
  * A View is an special element in a SVG documents that describes a rectangular area in the document.
  * Calling this method with a {@code viewId} will result in the specified view being positioned and scaled
  * to the viewport.  In other words, use {@link #renderToPicture()} to render the whole document, or use this
  * method instead to render just a part of it.
  * <p>
  * If the {@code <view>} could not be found, nothing will be drawn.
  *
  * @param viewId the id of a view element in the document that defines which section of the document is to be visible.
  * @param canvas the canvas to which the document should be rendered.
  */
renderViewToCanvas(String, Canvas) : void

/**
  * Renders this SVG document to a Canvas using the specified view defined in the document.
  * <p>
  * A View is an special element in a SVG documents that describes a rectangular area in the document.
  * Calling this method with a {@code viewId} will result in the specified view being positioned and scaled
  * to the viewport.  In other words, use {@link #renderToPicture()} to render the whole document, or use this
  * method instead to render just a part of it.
  * <p>
  * If the {@code <view>} could not be found, nothing will be drawn.
  *
  * @param viewId the id of a view element in the document that defines which section of the document is to be visible.
  * @param canvas the canvas to which the document should be rendered.
  * @param viewPort the bounds of the area on the canvas you want the SVG rendered, or null for the whole canvas.
  */
renderViewToCanvas(String, Canvas, RectF) : void

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