172 lines
4.8 KiB
C++
172 lines
4.8 KiB
C++
/*
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* Copyright 2019 University of Toronto
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Authors: Mario Badr, Sameh Attia and Tanner Young-Schultz
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*/
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#ifndef EZGL_CANVAS_HPP
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#define EZGL_CANVAS_HPP
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#include "ezgl/camera.hpp"
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#include "ezgl/rectangle.hpp"
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#include "ezgl/graphics.hpp"
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#include "ezgl/color.hpp"
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#include <cairo.h>
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#include <cairo-pdf.h>
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#include <cairo-svg.h>
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#include <gtk/gtk.h>
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#include <string>
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namespace ezgl {
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/**** Functions in this class are for ezgl internal use; application code doesn't need to call them ****/
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class renderer;
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/**
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* The signature of a function that draws to an ezgl::canvas.
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*/
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using draw_canvas_fn = void (*)(renderer*);
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/**
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* Responsible for creating, destroying, and maintaining the rendering context of a GtkWidget.
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*
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* Underneath, the class relies on a GtkDrawingArea as its GUI widget along with cairo to provide the rendering context.
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* The class connects to the relevant GTK signals, namely configure and draw events, to remain responsive.
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*
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* Each canvas is double-buffered. A draw callback (see: ezgl::draw_canvas_fn) is invoked each time the canvas needs to
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* be redrawn. This may be caused by the user (e.g., resizing the screen), but can also be forced by the programmer.
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*/
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class canvas {
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public:
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/**
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* Destructor.
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*/
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~canvas();
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/**
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* Get the name (identifier) of the canvas.
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*/
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char const *id() const
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{
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return m_canvas_id.c_str();
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}
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/**
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* Get the width of the canvas in pixels.
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*/
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int width() const;
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/**
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* Get the height of the canvas in pixels.
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*/
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int height() const;
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/**
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* Force the canvas to redraw itself.
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*
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* This will invoke the ezgl::draw_canvas_fn callback and queue a redraw of the GtkWidget.
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*/
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void redraw();
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/**
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* Get an immutable reference to this canvas' camera.
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*/
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camera const &get_camera() const
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{
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return m_camera;
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}
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/**
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* Get a mutable reference to this canvas' camera.
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*/
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camera &get_camera()
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{
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return m_camera;
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}
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/**
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* Create an animation renderer that can be used to draw on top of the current canvas
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*/
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renderer *create_animation_renderer();
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/**
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* print_pdf, print_svg, and print_png generate a PDF, SVG, or PNG output file showing
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* all the graphical content of the current canvas.
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*
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* @param file_name name of the output file
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* @return returns true if the function has successfully generated the output file, otherwise
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* failed due to errors such as out of memory occurs.
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*/
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bool print_pdf(const char *file_name, int width = 0, int height = 0);
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bool print_svg(const char *file_name, int width = 0, int height = 0);
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bool print_png(const char *file_name, int width = 0, int height = 0);
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protected:
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// Only the ezgl::application can create and initialize a canvas object.
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friend class application;
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/**
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* Create a canvas that can be drawn to.
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*/
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canvas(std::string canvas_id, draw_canvas_fn draw_callback, rectangle coordinate_system, color background_color);
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/**
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* Lazy initialization of the canvas class.
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*
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* This function is required because GTK will not send activate/startup signals to an ezgl::application until control
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* of the program has been reliquished. The GUI is not built until ezgl::application receives an activate signal.
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*/
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void initialize(GtkWidget *drawing_area);
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private:
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// Name of the canvas in XML.
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std::string m_canvas_id;
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// The function to call when the widget needs to be redrawn.
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draw_canvas_fn m_draw_callback;
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// The transformations between the GUI and the world.
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camera m_camera;
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// The background color of the drawing area
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color m_background_color;
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// A non-owning pointer to the drawing area inside a GTK window.
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GtkWidget *m_drawing_area = nullptr;
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// The off-screen surface that can be drawn to.
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cairo_surface_t *m_surface = nullptr;
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// The off-screen cairo context that can be drawn to
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cairo_t *m_context = nullptr;
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// The animation renderer
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renderer *m_animation_renderer = nullptr;
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private:
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// Called each time our drawing area widget has changed (e.g., in size).
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static gboolean configure_event(GtkWidget *widget, GdkEventConfigure *event, gpointer data);
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// Called each time we need to draw to our drawing area widget.
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static gboolean draw_surface(GtkWidget *widget, cairo_t *context, gpointer data);
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};
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}
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#endif //EZGL_CANVAS_HPP
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