problem with 'static' in class
The '::' isn't for resolving namespaces it is for resolving scope issues, of which namespaces are one possible application. Classes are another. Scope Resolution Operator.
Author
Yes but why can i say
instead of
but i have to say
I understand that drawImage needs to be defined within the 'graphics' scope but what about my gui example, i specify Button scope but it doesn't seem to need gui scope.
using namespace gui;void Button::draw() {}instead of
using namespace gui;void gui::Button::draw() {}but i have to say
using namespace graphics;void graphics::drawImage(...) {}I understand that drawImage needs to be defined within the 'graphics' scope but what about my gui example, i specify Button scope but it doesn't seem to need gui scope.
Because the only valid way that
can make sense is if it refers to an existing function named draw.
If you have:
what happens? :)
Using namespace tells the code to look there after looking locally. namespace foo { ... } does what you are describing.
void Button::draw() {}can make sense is if it refers to an existing function named draw.
If you have:
namespace Button { void draw();};namespace gui { namespace Button { void draw(); }}using namespace gui;void Button::draw() {}what happens? :)
Using namespace tells the code to look there after looking locally. namespace foo { ... } does what you are describing.
Author
I have another problem. Everything compiles ok but my static objects (static Image *upImg, *downImg, *hoverImg;) don't seem to be created.
I read them from an XML file:
Then create an OpenGL display list from the images:
The problem is that it crashes on the line "float ratio = height/img->height" saying that 'img' is not defined. When i click 'Add Watch' it says that the variable is out of scope. I reference it as Button::upImg and i get no compile errors so i don't get it. And the images are being created in getImageFromXML because they are not NULL.
EDIT: i just found out that if i directly substitute the code in getImageFromXML to where it is used, it works! But why? Am i not passing the Image pointer right?
I read them from an XML file:
void Button::loadImages() { // Defined in Button as 'static void loadImages()' XMLNode* node = readXML(UI_XML); node = node->getChild("button"); // Get <button> element XMLNode* child; for (int i = 0; child = node->getChild(i); i++) { if (!strcmp(child->getType(), "img")) { getImageFromXML(child, Button::upImg, "up"); getImageFromXML(child, Button::hoverImg, "hover"); getImageFromXML(child, Button::downImg, "down"); } if (!strcmp(child->getType(), "div")) { getDivFromXML(child, Button::divLeft, "left"); getDivFromXML(child, Button::divRight, "right"); } }}// In gui.hinline void getImageFromXML(XMLNode* node, Image* img, char* id) { if (!strcmp(node->getAttribute("id"), id)) img = new Image(node->getAttribute("file"));}Then create an OpenGL display list from the images:
void Button::update() { // 'void update()', virtual in Component // Create display lists to draw each image createComponentDL(dlUp, Button::upImg, x, y, width, height, Button::divLeft, Button::divRight); createComponentDL(dlHover, Button::hoverImg, x, y, width, height, Button::divLeft, Button::divRight); createComponentDL(dlDown, Button::downImg, x, y, width, height, Button::divLeft, Button::divRight);}// In gui.hinline void createComponentDL(GLuint &id, Image* img, int x, int y, int width, int height, int divLeft, int divRight) { float ratio = height/img->height;// Ratio of img to component size int posL = divLeft*ratio; // Position of divLeft on component int posR = divRight*ratio; // Position of divRight on component createList(id); // Draw left edge of image drawImage(img, x, y, posL, height, 0, 0, divLeft, img->height); // Draw middle section of image drawImage(img, x + posL, y, width - posL - posR, height, divLeft, 0, img->width - divLeft - divRight, img->height); // Draw right edge of image drawImage(img, x + width - posR, y, posR, height, img->width - divRight, 0, divRight, img->height); endList();}The problem is that it crashes on the line "float ratio = height/img->height" saying that 'img' is not defined. When i click 'Add Watch' it says that the variable is out of scope. I reference it as Button::upImg and i get no compile errors so i don't get it. And the images are being created in getImageFromXML because they are not NULL.
EDIT: i just found out that if i directly substitute the code in getImageFromXML to where it is used, it works! But why? Am i not passing the Image pointer right?
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
