c++ - C ++不同的类实例
问题描述
我是 C++ 新手，所以我不确定在这个问题的标题中要写什么。无论如何，我创建了一个类，其目的是创建一个标签，然后使用它一次又一次地创建另一个标签。
CALLBACK MyClassName::WndProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) noexcept -> LRESULT {
....
switch (msg) {
....
case WM_CREATE:
{
ControlLabel controlLabel, anotherLabel; //declare two control label
controlLabel.Label(123, hwnd); //Set new id and window handle for label
controlLabel.SetXPosition(68); //Set x position
controlLabel.SetYPosition(110); //Set y position
controlLabel.SetText("This is Label"); //Set the text of Label
controlLabel.SetFontSize(14); //Set the font size of the text
anotherLabel.Label(456, hwnd); //Create and set new id and window handle for another label
anotherLabel.SetXPosition(68); //Set x position of another label
anotherLabel.SetYPosition(140); //Set y position of another label
anotherLabel.SetText("This is another Label"); //Set the text of another label
anotherLabel.SetFontSize(14); //Set the font size of another label
break;
}
....
return ::DefWindowProcW(hwnd, msg, wparam, lparam);
}
我希望它有两个不同标签的输出，例如
这是标签
这是另一个标签
相反，我得到两个具有相同文本的标签。
这是另一个标签
这是另一个标签
无论如何，这是课程的完整来源。
控制标签.H
#pragma once
#ifndef CONTROLLABEL_H
#define CONTROLLABEL_H
#include "Header.h"
class ControlLabel {
public:
ControlLabel();
HWND Label(int Label_ID, HWND WindowHandle);
void SetXPosition(int xPosition);
void SetYPosition(int yPosition);
void SetText(string Text);
void SetFontFamily(string FontFamily);
void SetFontSize(int FontSize);
void SetFontColor(int R, int G, int B);
void SetBackgroundColor(int Rr, int Gg, int Bb, bool SetBGColor);
private:
void UpdateLabel();
void SetWidthAndHeights();
static std::wstring StringConverter(const std::string& s);
static LRESULT CALLBACK LabelProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData);
static HWND LabelHandle;
static SolidBrush vFontColor;
static string text, vFontFamily;
static bool SetBGColor;
static int xPosition, yPosition, width, height, LABEL_ID, vFontSize, R, G, B, BckR, BckG, BckB;
};
#endif
控制标签.cpp
#include "ControlLabel.h"
HWND ControlLabel::LabelHandle = NULL;
int ControlLabel::xPosition = 0;
int ControlLabel::yPosition = 0;
int ControlLabel::width = 0;
int ControlLabel::height = 0;
int ControlLabel::LABEL_ID = 0;
int ControlLabel::vFontSize = 12;
int ControlLabel::R = 0;
int ControlLabel::G = 0;
int ControlLabel::B = 0;
int ControlLabel::BckR = 0;
int ControlLabel::BckG = 0;
int ControlLabel::BckB = 0;
bool ControlLabel::SetBGColor = FALSE;
string ControlLabel::text = "Label";
string ControlLabel::vFontFamily = "Segoe UI";
ControlLabel::ControlLabel() {}
/** This function is used to convert string into std::wstring. **/
std::wstring ControlLabel::StringConverter(const std::string& s) {
int len;
int slength = (int)s.length() + 1;
len = MultiByteToWideChar(CP_ACP, 0, s.c_str(), slength, 0, 0);
wchar_t* buf = new wchar_t[len];
MultiByteToWideChar(CP_ACP, 0, s.c_str(), slength, buf, len);
std::wstring r(buf);
delete[] buf;
return r;
}
/** This function is used to automatically set the Width and Height of static control base on the length of the text. **/
void ControlLabel::SetWidthAndHeights() {
std::wstring fontFamilyTemp = StringConverter(vFontFamily);
std::wstring textTemp = StringConverter(text);
LPCWSTR textLabel = textTemp.c_str();
HDC hdc = GetDC(LabelHandle);//static control
HFONT hFont = CreateFont(
-MulDiv(vFontSize, GetDeviceCaps(hdc, LOGPIXELSX), 90), //calculate the actual cHeight.
0, 0, 0, // normal orientation
FW_NORMAL, // normal weight--e.g., bold would be FW_BOLD
false, false, false, // not italic, underlined or strike out
DEFAULT_CHARSET, OUT_OUTLINE_PRECIS, // select only outline (not bitmap) fonts
CLIP_DEFAULT_PRECIS, CLEARTYPE_QUALITY, VARIABLE_PITCH | FF_SWISS, fontFamilyTemp.c_str());
SIZE size;
HFONT oldfont = (HFONT)SelectObject(hdc, hFont);
GetTextExtentPoint32(hdc, textLabel, wcslen(textLabel), &size);
width = size.cx;
height = size.cy;
SelectObject(hdc, oldfont); //don't forget to select the old.
DeleteObject(hFont); //always delete the object after creating it.
ReleaseDC(LabelHandle, hdc); //alway reelase dc after using.
/*char buffer[100];
sprintf_s(buffer, "WIDTH: %d | HEIGHT: %d\n", width, height);
OutputDebugStringA(buffer);*/
}
/** This function will be called when new option is set. For example, fontSize is set. **/
void ControlLabel::UpdateLabel() {
if(LabelHandle != NULL) {
SetWidthAndHeights();
SetWindowPos(LabelHandle, nullptr, xPosition, yPosition, width, height, SWP_NOZORDER | SWP_NOOWNERZORDER);
InvalidateRect(LabelHandle, NULL, FALSE);
UpdateWindow(LabelHandle);
}
}
/** This is the callback function of static control. **/
LRESULT CALLBACK ControlLabel::LabelProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData) {
switch(uMsg) {
case WM_ERASEBKGND: {
if(SetBGColor) { //We only want to do this if the SetColor is modified to true, meaning we want to set the color of background.
RECT rect;
GetClientRect(hwnd, &rect);
FillRect((HDC)wParam, &rect, CreateSolidBrush(RGB(BckR, BckG, BckB))); //set titlebar background color.
return 1; //return 1, meaning we take care of erasing the background.
}
return 0;
}case WM_PAINT: {
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
Graphics g(hdc);
std::wstring fontFamilyTemp = StringConverter(vFontFamily);
std::wstring textTemp = StringConverter(text);
FontFamily theFontFamily(fontFamilyTemp.c_str());
Font font(&theFontFamily, vFontSize, FontStyleRegular, UnitPixel);
SolidBrush brush(Color(255, R, G, B));
PointF pointF(0.0f, 0.0f);
TextRenderingHint hint = g.GetTextRenderingHint(); // Get the text rendering hint.
g.SetTextRenderingHint(TextRenderingHintAntiAlias); // Set the text rendering hint to TextRenderingHintAntiAlias.
g.DrawString(textTemp.c_str(), -1, &font, pointF, &brush);
EndPaint(hwnd, &ps);
return TRUE;
}case WM_NCDESTROY: {
RemoveWindowSubclass(hwnd, LabelProc, uIdSubclass);
return 0;
}
}
return DefSubclassProc(hwnd, uMsg, wParam, lParam);
}
/** Use this function to create a Label. Parent or WindowHandle must be specified, this is where the Label will be drawn. Unique Label ID must be specified. **/
HWND ControlLabel::Label(int Label_ID, HWND WindowHandle) {
LABEL_ID = Label_ID;
LabelHandle = CreateWindowEx(0, L"STATIC", NULL, WS_CHILD | WS_VISIBLE | SS_OWNERDRAW, xPosition, yPosition, width, height, WindowHandle, NULL, NULL, NULL); //create the static control.
SetWindowSubclass(LabelHandle, &LabelProc, LABEL_ID, 0);
return LabelHandle;
}
/** Use this function to set the X Position of the Label. **/
void ControlLabel::SetXPosition(int xxPosition) {
if(LabelHandle != NULL) {
xPosition = xxPosition; //set xposition
UpdateLabel();
}
}
/** Use this function to set the Y Position of the Label. **/
void ControlLabel::SetYPosition(int yyPosition) {
if(LabelHandle != NULL) {
yPosition = yyPosition; //set xposition
UpdateLabel();
}
}
/** Use this function to set the text of the Label. **/
void ControlLabel::SetText(string ttext) {
if(LabelHandle != NULL) {
text = ttext; //set text
UpdateLabel();
}
}
/** Use this function to set the font family of the Label. **/
void ControlLabel::SetFontFamily(string font_family) {
if(LabelHandle != NULL) {
vFontFamily = font_family; //set font family
UpdateLabel();
}
}
/** Use this function to set the font size of the Label. **/
void ControlLabel::SetFontSize(int size) {
if(LabelHandle != NULL) {
vFontSize = size; //set font size
UpdateLabel();
}
}
/** Use this Function to set the font color of the Label using RGB. **/
void ControlLabel::SetFontColor(int Rr, int Gg, int Bb) {
if(LabelHandle != NULL) {
R = Rr;
G = Gg;
B = Bb;
UpdateLabel();
}
}
/** Use this Function to set the background color of the Label using RGB. Last parameter must be TRUE if you want to set your own background color. **/
void ControlLabel::SetBackgroundColor(int Rr, int Gg, int Bb, bool setColor) {
if(LabelHandle != NULL) {
SetBGColor = setColor;
BckR = Rr;
BckG = Gg;
BckB = Bb;
UpdateLabel();
}
}
解决方案
这没有任何意义，如果您的所有成员都是静态的，您将无法拥有不同的实例。
但是，由于窗口过程的回调需要是静态的，那么您将无法访问该函数内的那些非静态成员。
您可以做的是使用子类的dwRefData参数将您的类的实例传递给您的回调函数。然后，您可以强制转换该参数以访问非静态成员。
例如在您的::Label功能中；
SetWindowSubclass(LabelHandle, &LabelProc, LABEL_ID, <DWORD_PTR>(this)); //notice the last parameter, pass `this` instance so you can use `dwRefData`.
然后在您的回调中；
ControlLabel* controlLabel = reinterpret_cast<ControlLabel*>(dwRefData); //type cast the value of dwRefData.
controlLabel->text //you can now access your non-static variable text
controlLabel->vFontFamily //you can now access your non-static variable vFontFamily
类似的东西。
另一个问题是您不应该将回调声明为私有，而是将其公开。并且不要在 中声明你的ControlLabel对象WM_CREATE，而是让它成为全局对象。
ControlLabel controlLabel, anotherLabel; //declare two control label as Global.
CALLBACK MyClassName::WndProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) noexcept -> LRESULT {
....
switch (msg) {
....
case WM_CREATE:
{
controlLabel.Label(123, hwnd); //Set new id and window handle for label
...
anotherLabel.Label(456, hwnd); //Create and set new id and window handle for another label
...
break;
}
....
return ::DefWindowProcW(hwnd, msg, wparam, lparam);
}
无论如何，我注意到你的类没有析构函数来破坏你的LabelHandle. 确保这样做。
ControlLabel.h //In your ControlLabel.h
~ControlLabel(); //should be in public
ControlLabel.cpp //In your ControlLabel.cpp
ControlLabel::~ControlLabel() {
if(LabelHandle) DestroyWindow(LabelHandle); //destroy when done.
}
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