Android图形库Skia(四)－生成PDF
Android图形库Skia(四)－生成PDF
本文主要记录使用skia库生成pdf文件的过程，其实skia并不仅仅能在Android系统中使用，在一般的嵌入式Linux系统上也可以使用的。标题就以以前的写法写了。本文基于Android图形库Skia(一)－基本测试生成PNG图片和Android图形库Skia(三)－结合Freetype显示文字。直接给出例子：
/*SimplePDFdemoutilizingSkiatoolkit.
*Authoredbykangear<kangear@163.com>
*/
#include"SkBitmap.h"
#include"SkDevice.h"
#include"SkPaint.h"
#include"SkRect.h"
#include"SkImageEncoder.h"
#include"SkPDFCatalog.h"
#include"SkPDFDevice.h"
#include"SkPDFStream.h"
#include"SkPDFTypes.h"
#include"SkPDFDocument.h"
#include<stdio.h>
#include<unistd.h>
#include"SkTypeface.h"
//draw_content()
intmain()
{
//Declarearasterbitmap,whichhasanintegerwidthandheight,
//andaformat(config),andapointertotheactualpixels.
//BitmapscanbedrawnintoaSkCanvas,buttheyarealsousedto
//specifythetargetofaSkCanvas'drawingoperations.
SkBitmapbitmap;
bitmap.setConfig(SkBitmap::kARGB_8888_Config,200,200);
bitmap.allocPixels();
SkPDFDevice*dev=newSkPDFDevice(827,1169);
SkAutoUnrefaur(dev);
//ACanvasencapsulatesallofthestateaboutdrawingintoa
//device(bitmap).Thisincludesareferencetothedeviceitself,
//andastackofmatrix/clipvalues.Foranygivendrawcall(e.g.
//drawRect),thegeometryoftheobjectbeingdrawnistransformed
//bytheconcatenationofallthematricesinthestack.The
//transformedgeometryisclippedbytheintersectionofallofthe
//clipsinthestack.
SkCanvascanvas(dev);
//SkPaintclassholdsthestyleandcolorinformationabouthowto
//drawgeometries,textandbitmaps.
SkPaintpaint;
//SkIRectholdsfour32bitintegercoordinatesforarectangle.
SkRectr;
paint.setARGB(255,255,0,0);
r.set(25,25,145,145);
canvas.drawRect(r,paint);/**Drawthespecifiedrectangleusing
thespecifiedpaint.Therectangle
willbefilledorstrokedbasedon
theStyleinthepaint.*/
paint.setARGB(255,0,255,0);
r.offset(20,20);
canvas.drawRect(r,paint);
paint.setARGB(255,0,0,255);
r.offset(20,20);
canvas.drawRect(r,paint);
constchargText[]="123平34凡之路12！";
//SkTypeface*font=SkTypeface::CreateFromFile("DroidSansFallbackFull.ttf");
//usr/share/fonts/truetype/msttcorefonts/DroidSansFallbackFull.ttf
SkTypeface*font=SkTypeface::CreateFromName("DroidSansFallback",SkTypeface::kNormal);
if(font)
{
paint.setARGB(255,255,0,0);
paint.setTypeface(font);
paint.setTextSize(25);
canvas.drawText(gText,sizeof(gText)/sizeof(gText[0]),0,25,paint);
}
else
{
printf("font==null!\n");
}
//SkImageEncoderisthebaseclassforencodingcompressedimages
//fromaspecificSkBitmap.
SkImageEncoder::EncodeFile("snapshot.png",bitmap,
SkImageEncoder::kPNG_Type,
/*Qualityrangesfrom0..100*/100);
//saveasapdffile
SkPDFDocumentdoc;
doc.appendPage(dev);
SkDynamicMemoryWStreampdf_stream;
doc.emitPDF(&pdf_stream);
write(STDOUT_FILENO,pdf_stream.getStream(),pdf_stream.getOffset());
return0;
}
/*
build:
g++\
-I./include\
-I./include/core\
-I./include/images\
-I./include/config\
-I./include/pdf/\
-Wall-otest-skia./test-skia.cpp\
out/src/images/SkImageDecoder_libpng.o\
out/libskia.a\
`pkg-configfreetype2--libs--cflags`\
`pkg-configlibpng--libs--cflags`\
-lpthread-g
run:
./test-skia>test.pdf
*/
效果：
注意事项：生成PDF时，如果使用SkTypeface::CreateFromFile方法创建字体face，属于内置字体，会造成在其它环境下PDF中字体无法正常显示。使用Adobereader会提示：
打印效果：
文字版本：
Cannotextracttheembeddedfont‘DroidSansFallback’.Somecharactersmaynotdisplayorprintcorrectly.
参考文档：
1.https://code.google.com/p/skia/wiki/PDFTheoryOfOperation
2.List_of_typefaces
3.PDFReference