Add examples/SVG_File_Surface.cxx and refer to it in the doc of class Fl_Surface_Device
This example code shows how to subclass Fl_Surface_Device and Fl_Graphics_Driver to endow FLTK with a new kind of graphics output. git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12980 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
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Manolo Gouy
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f6a7602cfc
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51389ca460
@ -51,6 +51,17 @@ class Fl_Widget;
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</ol>
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For back-compatibility, it is also possible to use the Fl_Surface_Device::set_current() member function
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to change the current drawing surface, once to the new surface, once to the previous one.
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Class Fl_Surface_Device can also be derived to define new kinds of graphical output
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usable with FLTK drawing functions.
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An example would be to draw to an SVG file. This would require to create a new class,
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say SVG_Surface, derived from class Fl_Surface_Device, and another new class,
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say SVG_Graphics_Driver, derived from class Fl_Graphics_Driver.
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Class SVG_Graphics_Driver should implement all virtual methods of the Fl_Graphics_Driver class
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to support all FLTK drawing functions and have them draw into SVG files. Alternatively,
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class SVG_Graphics_Driver could implement only some virtual methods, and only part of
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the FLTK drawing API would be usable when drawing to SVG files
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(see examples/SVG_File_Surface.cxx for a small, working implementation of this procedure).
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*/
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class FL_EXPORT Fl_Surface_Device {
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/** The graphics driver in use by this surface. */
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@ -72,14 +72,6 @@ struct Fl_Fontdesc;
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drawing operations are directed to another drawing surface by Fl_Surface_Device::push_current() /
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Fl_Surface_Device::pop_current() / Fl_Surface_Device::set_current().
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The Fl_Graphics_Driver class is of interest if one wants to perform new kinds of drawing operations.
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An example would be to draw to an SVG file. This would require to create a new class,
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say SVG_Graphics_Driver, derived from class Fl_Graphics_Driver, and another new class,
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say SVG_Surface, derived from class Fl_Surface_Device. The new SVG_Graphics_Driver class should
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implement all virtual methods of the Fl_Graphics_Driver class to support all FLTK drawing functions
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and have them draw into SVG files. Alternatively, class SVG_Graphics_Driver could implement only some
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virtual methods, and only part of FLTK drawing functions would be usable when drawing to SVG files.
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The Fl_Graphics_Driver class is essential for developers of the FLTK library.
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Each platform supported by FLTK requires to create a derived class of Fl_Graphics_Driver that
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implements all its virtual member functions according to the platform.
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234
examples/SVG_File_Surface.cxx
Normal file
234
examples/SVG_File_Surface.cxx
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@ -0,0 +1,234 @@
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#include <FL/fl_draw.H>
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#include <stdio.h>
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#include <FL/Fl_Device.H>
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#include <FL/Fl_Graphics_Driver.H>
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#include <FL/Fl.H>
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#include <FL/Fl_Window.H>
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#include <FL/Fl_Box.H>
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class SVG_Graphics_Driver : public Fl_Graphics_Driver {
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FILE *out_;
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int width_;
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const char *linecap_;
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uchar red_, green_, blue_;
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public:
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SVG_Graphics_Driver(FILE*);
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~SVG_Graphics_Driver();
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FILE* file() {return out_;}
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protected:
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const char *family_;
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const char *bold_;
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const char *style_;
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void rect(int x, int y, int w, int h);
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void rectf(int x, int y, int w, int h);
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void line_style(int style, int width, char *dashes=0);
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void line(int x1, int y1, int x2, int y2);
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void font_(int f, int s);
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void font(int f, int s);
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void draw(const char *str, int n, int x, int y);
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void draw(const char*, int, float, float) ;
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void draw(int, const char*, int, int, int) ;
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void rtl_draw(const char*, int, int, int) {}
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void color(uchar r, uchar g, uchar b);
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void color(Fl_Color c);
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void draw_image(const uchar*, int, int, int, int, int, int) {}
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void draw_image_mono(const uchar*, int, int, int, int, int, int) {}
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void draw_image(void (*)(void*, int, int, int, uchar*), void*, int, int, int, int, int) {}
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void draw_image_mono(void (*)(void*, int, int, int, uchar*), void*, int, int, int, int, int) {}
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void draw(Fl_RGB_Image*, int, int, int, int, int, int) {}
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void draw(Fl_Pixmap*, int, int, int, int, int, int) {}
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void draw(Fl_Bitmap*, int, int, int, int, int, int) {}
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double width(const char*, int) ;
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int height() ;
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int descent() ;
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void push_clip(int x, int y, int w, int h) {}
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void pop_clip(){}
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void xyline(int x, int y, int x1){}
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void xyline(int x, int y, int x1, int y2){}
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void yxline(int x, int y, int y1){}
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void yxline(int x, int y, int y1, int x2){}
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virtual void point(int x, int y) {}
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virtual void line(int x, int y, int x1, int y1, int x2, int y2) {}
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virtual void xyline(int x, int y, int x1, int y2, int x3) {}
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virtual void yxline(int x, int y, int y1, int x2, int y3) {}
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virtual void loop(int x0, int y0, int x1, int y1, int x2, int y2) {}
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virtual void loop(int x0, int y0, int x1, int y1, int x2, int y2, int x3, int y3) {}
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virtual void polygon(int x0, int y0, int x1, int y1, int x2, int y2) {}
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virtual void polygon(int x0, int y0, int x1, int y1, int x2, int y2, int x3, int y3) {}
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virtual int clip_box(int x, int y, int w, int h, int &X, int &Y, int &W, int &H) {return 0;}
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virtual int not_clipped(int x, int y, int w, int h) {return 0;}
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virtual void push_no_clip() {}
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virtual void begin_complex_polygon() {}
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virtual void transformed_vertex(double xf, double yf) {}
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virtual void vertex(double x, double y) {}
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virtual void end_points() {}
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virtual void end_line() {}
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virtual void end_loop() {}
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virtual void end_polygon() {}
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virtual void end_complex_polygon() {}
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virtual void gap() {}
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virtual void circle(double x, double y, double r) {}
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virtual void arc(int x, int y, int w, int h, double a1, double a2) {}
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virtual void pie(int x, int y, int w, int h, double a1, double a2) {}
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virtual Fl_Bitmask create_bitmask(int w, int h, const uchar *array) {return 0;}
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virtual void delete_bitmask(Fl_Bitmask bm) {}
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};
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class SVG_File_Surface : public Fl_Surface_Device {
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int width_, height_;
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public:
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SVG_File_Surface(int width, int height, FILE*);
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int width() { return width_; }
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int height() { return height_; }
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~SVG_File_Surface();
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};
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SVG_Graphics_Driver::SVG_Graphics_Driver(FILE *f) {
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out_ = f;
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width_ = 1;
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linecap_ = "butt";
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family_ = "";
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bold_ = "";
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style_ = "";
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red_ = green_ = blue_ = 0;
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}
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SVG_Graphics_Driver::~SVG_Graphics_Driver()
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{
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}
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void SVG_Graphics_Driver::rect(int x, int y, int w, int h) {
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fprintf(out_, "<rect x=\"%d\" y=\"%d\" width=\"%d\" height=\"%d\" "
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"fill=\"none\" stroke=\"rgb(%u,%u,%u)\" stroke-width=\"%d\"/>\n", x, y, w, h, red_, green_, blue_, width_);
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}
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void SVG_Graphics_Driver::rectf(int x, int y, int w, int h) {
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fprintf(out_, "<rect x=\"%d\" y=\"%d\" width=\"%d\" height=\"%d\" "
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"fill=\"rgb(%u,%u,%u)\" />\n", x, y, w, h, red_, green_, blue_);
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}
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void SVG_Graphics_Driver::line(int x1, int y1, int x2, int y2) {
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fprintf(out_,
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"<line x1=\"%d\" y1=\"%d\" x2=\"%d\" y2=\"%d\" "
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"style=\"stroke:rgb(%u,%u,%u);stroke-width:%d;stroke-linecap:%s\" />\n",
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x1,y1,x2,y2, red_, green_, blue_, width_, linecap_);
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}
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void SVG_Graphics_Driver::font_(int ft, int s) {
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Fl_Graphics_Driver::font(ft, s);
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int famnum = ft/4;
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if (famnum == 0) family_ = "Helvetica";
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else if (famnum == 1) family_ = "Courier";
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else family_ = "Times";
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int modulo = ft % 4;
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int use_bold = modulo == 1 || modulo == 3;
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int use_italic = modulo >= 2;
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bold_ = ( use_bold ? " font-weight=\"bold\"" : "" );
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style_ = ( use_italic ? " font-style=\"italic\"" : "" );
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if (use_italic && famnum != 2) style_ = " font-style=\"oblique\"";
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}
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void SVG_Graphics_Driver::font(int ft, int s) {
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Fl_Display_Device::display_device()->driver()->font(ft, s);
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font_(ft, s);
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}
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void SVG_Graphics_Driver::line_style(int style, int width, char *dashes) {
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if (width == 0) width = 1;
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width_ = width;
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if (style & FL_CAP_SQUARE) linecap_ = "square";
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if (style & FL_CAP_ROUND) linecap_ = "round";
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else linecap_ = "butt";
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}
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void SVG_Graphics_Driver::draw(const char *str, int n, int x, int y) {
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// Caution: Internet Explorer ignores the xml:space="preserve" attribute
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// work-around: replace all spaces by no-break space = U+00A0 = 0xC2-0xA0 (UTF-8) before sending to IE
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fprintf(out_, "<text x=\"%d\" y=\"%d\" font-family=\"%s\"%s%s font-size=\"%d\" "
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"xml:space=\"preserve\" "
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" fill=\"rgb(%u,%u,%u)\" textLength=\"%d\">%.*s</text>\n",x, y, family_, bold_, style_, size(), red_, green_, blue_, (int)width(str, n), n, str);
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}
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void SVG_Graphics_Driver::draw(const char* str, int n, float fx, float fy) {
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return draw(str, n, (int)fx, (int)fy);
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}
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void SVG_Graphics_Driver::draw(int angle, const char* str, int n, int x, int y) {
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fprintf(out_, "<g transform=\"translate(%d,%d) rotate(%d)\">", x, y, -angle);
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draw(str, n, 0, 0);
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fputs("</g>\n", out_);
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}
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void SVG_Graphics_Driver::color(Fl_Color c) {
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Fl_Graphics_Driver::color(c);
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Fl::get_color(c, red_, green_, blue_);
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}
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void SVG_Graphics_Driver::color(uchar r, uchar g, uchar b) {
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red_ = r;
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green_ = g;
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blue_ = b;
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}
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double SVG_Graphics_Driver::width(const char* str, int l) {
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return Fl_Display_Device::display_device()->driver()->width(str, l);
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}
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int SVG_Graphics_Driver::height() {
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return Fl_Display_Device::display_device()->driver()->height();
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}
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int SVG_Graphics_Driver::descent() {
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return Fl_Display_Device::display_device()->driver()->descent();
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}
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SVG_File_Surface::SVG_File_Surface(int w, int h, FILE *f) : Fl_Surface_Device(NULL) {
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fprintf(f,
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"<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n"
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"<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \n"
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"\"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n"
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"<svg width=\"%dpx\" height=\"%dpx\" viewBox=\"0 0 %d %d\"\n"
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"xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\">\n", w, h, w, h);
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width_ = w; height_ = h;
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driver(new SVG_Graphics_Driver(f));
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}
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SVG_File_Surface::~SVG_File_Surface() {
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SVG_Graphics_Driver *driver = (SVG_Graphics_Driver*)this->driver();
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fputs("</svg>\n", driver->file());
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fflush(driver->file());
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delete driver;
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}
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int main(int argc, char **argv) {
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Fl_Window *window = new Fl_Window(340,180);
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Fl_Box *box = new Fl_Box(20,40,300,100,"Hello, World!");
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box->box(FL_UP_BOX);
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box->labelfont(FL_BOLD+FL_ITALIC);
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box->labelsize(36);
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box->labeltype(FL_SHADOW_LABEL);
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window->end();
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window->show(argc, argv);
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FILE *out = fl_fopen("hello.svg", "w");
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if (out) {
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SVG_File_Surface *svg = new SVG_File_Surface(box->w(), box->h(), out);
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Fl_Surface_Device::push_current(svg);
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fl_color(box->color());
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fl_rectf(0, 0, box->w(), box->h());
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fl_font(box->labelfont(), 36);
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fl_color(box->labelcolor());
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fl_draw(box->label(), 5, 50);
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Fl_Surface_Device::pop_current();
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delete svg;
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fclose(out);
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}
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return Fl::run();
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}
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