129 lines
4.4 KiB
C++
129 lines
4.4 KiB
C++
//
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// Fl_Cairo_Window header file for the Fast Light Tool Kit (FLTK).
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//
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// Copyright 1998-2023 by Bill Spitzak and others.
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//
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// This library is free software. Distribution and use rights are outlined in
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// the file "COPYING" which should have been included with this file. If this
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// file is missing or damaged, see the license at:
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//
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// https://www.fltk.org/COPYING.php
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//
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// Please see the following page on how to report bugs and issues:
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//
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// https://www.fltk.org/bugs.php
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//
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/** \file FL/Fl_Cairo_Window.H
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\brief Fl_Cairo_Window, an FLTK window incorporating a Cairo draw callback.
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*/
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#ifndef FL_CAIRO_WINDOW_H
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# define FL_CAIRO_WINDOW_H
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#include <FL/fl_config.h>
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# ifdef FLTK_HAVE_CAIRO
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// Cairo is currently supported for the following platforms:
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// Win32, Apple Quartz, X11, Wayland
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# include <FL/Fl.H>
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# include <FL/Fl_Double_Window.H>
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/**
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\addtogroup group_cairo
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@{
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*/
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/**
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This defines an FLTK window with Cairo support.
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This class overloads the virtual draw() method for you,
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so that the only thing you have to do is to provide your Cairo code.
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All Cairo context handling is achieved transparently.
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The default coordinate system for Cairo drawing commands within Fl_Cairo_Window
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is FLTK's coordinate system, where the `x,y,w,h` values are relative to the
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top/left corner of the Fl_Cairo_Window, as one would expect with regular
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FLTK drawing commands, e.g.: `(0 ≤ x ≤ w-1), (0 ≤ y ≤ h-1)`.
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\b Example:
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\code
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static void my_cairo_draw_cb(Fl_Cairo_Window *window, cairo_t *cr) {
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// Draw an "X"
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const double xmax = (window->w() - 1);
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const double ymax = (window->h() - 1);
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cairo_set_line_width(cr, 1.00); // line width for drawing
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cairo_set_source_rgb(cr, 1.0, 0.5, 0.0); // orange
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cairo_move_to(cr, 0.0, 0.0); cairo_line_to(cr, xmax, ymax); // draw diagonal "\"
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cairo_move_to(cr, 0.0, ymax); cairo_line_to(cr, xmax, 0.0); // draw diagonal "/"
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cairo_stroke(cr); // stroke the lines
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}
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\endcode
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The FLTK coordinate system differs from the default native Cairo coordinate system
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which uses normalized `(0.0 … 1.0)` values for x and y, e.g.: `(0 ≤ x ≤ 1.0), (0 ≤ y ≤ 1.0)`.
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So beware of this when copy/pasting Cairo example programs that assume normalized values.
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If need be, you can revert to the Cairo coordinate system by simply calling `cairo_scale()`
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with the widget's `w()` and `h()` values. \b Example:
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\code
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static void my_cairo_draw_cb(Fl_Cairo_Window *window, cairo_t *cr) {
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cairo_scale(cr, window->w(), window->h()); // use Cairo's default coordinate system
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[..use 0.0 to 1.0 values from here on..]
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}
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\endcode
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\see examples/cairo-draw-x.cxx
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\see test/cairo_test.cxx
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\note Class Fl_Cairo_Window requires the FLTK library to have been built with
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CMake option OPTION_CAIRO or configure --enable-cairo.
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\note You can alternatively define your custom Cairo FLTK window,
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and thus at least override the draw() method to provide custom Cairo
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support. In this case you will probably use Fl::cairo_make_current(Fl_Window*)
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to attach a context to your window. You should do this only when your window is
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the current window. \see Fl_Window::current()
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*/
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class FL_EXPORT Fl_Cairo_Window : public Fl_Double_Window {
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public:
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Fl_Cairo_Window(int W, int H, const char *L = 0)
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: Fl_Double_Window(W, H, L), draw_cb_(0) {}
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Fl_Cairo_Window(int X, int Y, int W, int H, const char *L = 0)
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: Fl_Double_Window(X, Y, W, H, L), draw_cb_(0) {}
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protected:
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/** Overloaded to provide Cairo callback support. */
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void draw() FL_OVERRIDE {
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Fl_Double_Window::draw();
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if (draw_cb_) { // call the Cairo draw callback
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// manual method ? if yes explicitly get a cairo_context here
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if (!Fl::cairo_autolink_context())
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Fl::cairo_make_current(this);
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draw_cb_(this, Fl::cairo_cc());
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// flush Cairo drawings: necessary at least for Windows
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Fl::cairo_flush(Fl::cairo_cc());
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}
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}
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public:
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/** The Cairo draw callback prototype you need to implement. */
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typedef void (*cairo_draw_cb) (Fl_Cairo_Window* self, cairo_t* def);
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/**
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You must provide a draw callback that implements your Cairo rendering.
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This method permits you to set your Cairo callback to \p cb.
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*/
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void set_draw_cb(cairo_draw_cb cb) { draw_cb_ = cb; }
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private:
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cairo_draw_cb draw_cb_;
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};
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/** @} */
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# endif // FLTK_HAVE_CAIRO
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#endif // FL_CAIRO_WINDOW_H
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