From 1dd492958567493c0e62f5d2614f1a46c50cb7e1 Mon Sep 17 00:00:00 2001
From: Albrecht Schlosser <albrechts.fltk@online.de>
Date: Fri, 5 Jun 2020 21:11:15 +0200
Subject: [PATCH] Add two virtual methods to class Fl_Image
(1) The new virtual method Fl_Image::release() which is equivalent to
'delete this' automatically extends to Fl_Shared_Image::release()
which makes the latter method virtual.
This new method in the base class makes Fl_Image::release() callable
on all objects derived from Fl_Image.
(2) Add virtual method Fl_Shared_Image *Fl_Image::as_shared_image()
This new method can be used to detect whether an Fl_Image instance
is an Fl_Shared_Image or not.
---
FL/Fl_Image.H | 44 ++++++++++++++++++++++++++++++++++++++++++++
FL/Fl_Shared_Image.H | 4 ++++
2 files changed, 48 insertions(+)
diff --git a/FL/Fl_Image.H b/FL/Fl_Image.H
index c6fb55967..aafd39742 100644
--- a/FL/Fl_Image.H
+++ b/FL/Fl_Image.H
@@ -164,6 +164,50 @@ public:
*/
const char * const *data() const {return data_;}
int fail();
+ /**
+ Releases an Fl_Image - the same as '\p delete \p this'.
+
+ This virtual method is for almost all image classes the same as calling
+ \code
+ delete image;
+ \endcode
+ where image is an \p Fl_Image \p * pointer.
+
+ However, for subclass Fl_Shared_Image this virtual method is
+ reimplemented and maintains shared images.
+
+ This virtual method makes it possible to \p delete all image types in
+ the same way by calling
+ \code
+ image->release();
+ \endcode
+
+ Reasoning: If you have an 'Fl_Image *' pointer and don't know if the
+ object is one of the class Fl_Shared_Image or any other subclass of
+ Fl_Image (for instance Fl_RGB_Image) then you can't just use operator
+ delete since this is not appropriate for Fl_Shared_Image objects.
+
+ The virtual method release() handles this properly.
+
+ \since 1.4.0 in the base class Fl_Image and virtual in Fl_Shared_Image
+ */
+ virtual void release() {
+ delete this;
+ }
+
+ /** Returns whether an image is an Fl_Shared_Image or not.
+
+ This virtual method returns a pointer to an Fl_Shared_Image if this
+ object is an instance of Fl_Shared_Image or NULL if not. This can be
+ used to detect if a given Fl_Image object is a shared image, i.e.
+ derived from Fl_Shared_Image.
+
+ \since 1.4.0
+ */
+ virtual class Fl_Shared_Image *as_shared_image() {
+ return 0;
+ }
+
Fl_Image(int W, int H, int D);
virtual ~Fl_Image();
virtual Fl_Image *copy(int W, int H);
diff --git a/FL/Fl_Shared_Image.H b/FL/Fl_Shared_Image.H
index 89d40d9ac..f68ec7af0 100644
--- a/FL/Fl_Shared_Image.H
+++ b/FL/Fl_Shared_Image.H
@@ -99,6 +99,10 @@ public:
void release();
void reload();
+ virtual Fl_Shared_Image *as_shared_image() {
+ return this;
+ }
+
virtual Fl_Image *copy(int W, int H);
Fl_Image *copy() { return Fl_Image::copy(); }
virtual void color_average(Fl_Color c, float i);
--
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