UE 消息打印
参数均按顺序给出1. GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Red, TEXT(" Hello "));
函数申明：
/*** This function will add a debug message to the onscreen message list.* It will be displayed for FrameCount frames.* @paramKeyA unique key to prevent the same message from being added multiple times.* @paramTimeToDisplay How long to display the message, in seconds.* @paramDisplayColor The color to display the text in.* @paramDebugMessage The message to display.*/void AddOnScreenDebugMessage(int32 Key, float TimeToDisplay, FColor DisplayColor, const FString& DebugMessage, bool bNewerOnTop = true, const FVector2D& TextScale = FVector2D::UnitVector);
此外，两个默认参数
bNewerOnTop(true)：是否顶层显示，
TextScale(FVector2D::UnitVector)：字体比例。
此外，RemoveOnScreenDebugMessage(Key) 可以根据具体的Key去除正在显示的消息。
此外，可以使用宏定义简化操作
#define PRINT(String) {if (GEngine){GEngine->AddOnScreenDebugMessage(-1,10.0f,FColor::Red,*(String));}}2. UKismetSystemLibrary::PrintString(this,TEXT(" Hello "));
函数申明：
/** * Prints a string to the log, and optionally, to the screen * If Print To Log is true, it will be visible in the Output Log window.Otherwise it will be logged only as 'Verbose', so it generally won't show up. * * @param InString The string to log out * @param bPrintToScreenWhether or not to print the output to the screen * @param bPrintToLog Whether or not to print the output to the log * @param bPrintToConsole Whether or not to print the output to the console * @param TextColor Whether or not to print the output to the console * @param Duration The display duration (if Print to Screen is True). Using negative number will result in loading the duration time from the config. */UFUNCTION(BlueprintCallable, meta=(WorldContext="WorldContextObject", CallableWithoutWorldContext, Keywords = "log print", AdvancedDisplay = "2", DevelopmentOnly), Category="Utilities|String")static void PrintString(const UObject* WorldContextObject, const FString& InString = FString(TEXT("Hello")), bool bPrintToScreen = true, bool bPrintToLog = true, FLinearColor TextColor = FLinearColor(0.0, 0.66, 1.0), float Duration = 2.f);
原注释不祥，给中文注释
const UObject* WorldContextObject：用于得到当前世界的上下文
const FString& InString：文本内容
bool bPrintToScreen：是否打印到屏幕
bool bPrintToLog：是否打印到Log
FLinearColor TextColor：文本颜色
float Duration：显示持续时间
此外，注意 #include "Kismet/KismetSystemLibrary.h"
此外，还有 PrintText() 函数用于打印 FText 类型的变量。
此外，可以看出，源代码的命名都十分规范，其含义一目了然。
3. UE_LOG(LogTemp, Log, TEXT(" Hello "));
宏定义 ：
/*** Amacro that outputs a formatted message to log if a given logging category is active at a given verbosity level * @param CategoryName name of the logging category * @param Verbosity verbosity level to test against * @param Format format text **/#define UE_LOG(CategoryName, Verbosity, Format, ...) \ { \ CA_CONSTANT_IF((ELogVerbosity::Verbosity & ELogVerbosity::VerbosityMask) <= ELogVerbosity::COMPILED_IN_MINIMUM_VERBOSITY && (ELogVerbosity::Warning & ELogVerbosity::VerbosityMask) <= FLogCategory##CategoryName::CompileTimeVerbosity) \ { \ UE_INTERNAL_LOG_IMPL(CategoryName, Verbosity, Format, ##__VA_ARGS__); \ } \ }
打印消息到Output Log ,在编辑器的 Windows/Log/OutputLog 或者Rider的 Unreal模板 可见，内容保存在 \项目文件夹\Saved\Logs 。
4. UE_LOG(LogDiy, Error, TEXT(" Hello "));
宏定义：
/** * @param CategoryName 决定Log的名称 * @param DefaultVerbosity 决定Log的颜色 * @param CompileTimeVerbosity 决定Log的最大级别**/#define DECLARE_LOG_CATEGORY_EXTERN(CategoryName, DefaultVerbosity, CompileTimeVerbosity) \ extern struct FLogCategory##CategoryName : public FLogCategory<ELogVerbosity::DefaultVerbosity, ELogVerbosity::CompileTimeVerbosity> \ { \ FORCEINLINE FLogCategory##CategoryName() : FLogCategory(TEXT(#CategoryName)) {} \ } CategoryName;/*** @param **CategoryName** 定义的Log名称 **/#define DEFINE_LOG_CATEGORY(CategoryName) FLogCategory##CategoryName CategoryName;
在.h文件添加 DECLARE_LOG_CATEGORY_EXTERN(CategoryName, DefaultVerbosity, CompileTimeVerbosity);
在.cpp文件添加 DEFINE_LOG_CATEGORY(CategoryName);
在.cpp文件使用 UE_LOG(CategoryName, Log, TEXT(“Hello”))；
代码测试(含多参数)
TestLog.h
// Fill out your copyright notice in the Description page of Project Settings.#pragma once#include "CoreMinimal.h"#include "GameFramework/Actor.h"#include "TestLog.generated.h"/** * @param CategoryName 决定Log的名称 * @param DefaultVerbosity 决定Log的颜色 * @param CompileTimeVerbosity 决定Log的最大级别 * 在.h文件使用DECLARE_LOG_CATEGORY_EXTERN(CategoryName, DefaultVerbosity, CompileTimeVerbosity); ** @param CategoryName 定义的Log名称 * 在.cpp文件使用DEFINE_LOG_CATEGORY(CategoryName);**/DECLARE_LOG_CATEGORY_EXTERN(LogForInit, Log, All);/** * @brief Log测试 */UCLASS()class MICROWORLD_API ATestLog : public AActor{ GENERATED_BODY()protected: /** * @brief 打印所调用的函数 * @param Condition 打印的方式 */ UFUNCTION(BlueprintCallable) bool SwitchLog(int32 Condition);};
TestLog.cpp
// Fill out your copyright notice in the Description page of Project Settings.#include "TestLog.h"#include "Kismet/KismetSystemLibrary.h"DEFINE_LOG_CATEGORY(LogForInit);bool ATestLog::SwitchLog(int32 Condition){ bool bResult = true; switch (Condition){ case 1: { //使用AddOnScreenDebugMessage,打印到屏幕 if (GEngine != nullptr){ GEngine->AddOnScreenDebugMessage(-1, 5.0f, FColor::Red, TEXT("Log by GEngine.AddOnScreenDebugMessage")); } break; } case 2: { //使用PrintString,打印到屏幕 UKismetSystemLibrary::PrintString(this, TEXT("Log by UKismetSystemLibrary.PrintString")); break; } case 3: { //使用Log UE_LOG(LogTemp, Log, TEXT("Log by UE_Log in Different Level")); break; } case 4: { //使用自定义Log UE_LOG(LogForInit, Error, TEXT("Log by UE_Log LogForInit")); break; } case 5: { //带参数的打印 //与c语言的Printf函数类似,格式符一致 //主要是对TEXT字符串做处理,若不是基础类型或者FString类型，先转换为FString类型在打印 //注意浮点数默认打印6位小数 const bool ParamBool = true; const int32 ParamInt = 1; const float ParamFloat = 1233.1415f; const double ParamDouble = 3.1415926; //更为简单的字符串插值 //TArray<FStringFormatArg> Args; //Args.Add(FStringFormatArg(FString::SanitizeFloat(ParamDouble,10))); //const FString Message =FString::Format(TEXT("{0}"),Args); const FString Message = FString::Printf(TEXT("Log by Format Parameter:\ \nParamBool:%s,\nParamInt:%d,\nParamDouble:%-20.3f,\nParamDouble:%.5lf") , (ParamBool ? TEXT("true") : TEXT("false")), ParamInt, ParamFloat, ParamDouble); if (GEngine != nullptr){ GEngine->AddOnScreenDebugMessage(-1, 20.0f, FColor::Red, *Message); } } default: { bResult = false; break; } } return bResult;}
Log级别
enum Type : uint8 { /** Not used */ NoLogging = 0, /** Always prints a fatal error to console (and log file) and crashes (even if logging is disabled) */ Fatal, /** * Prints an error to console (and log file). * Commandlets and the editor collect and report errors. Error messages result in commandlet failure. */ Error, /** * Prints a warning to console (and log file). * Commandlets and the editor collect and report warnings. Warnings can be treated as an error. */ Warning, /** Prints a message to console (and log file) */ Display, /** Prints a message to a log file (does not print to console) */ Log, /** * Prints a verbose message to a log file (if Verbose logging is enabled for the given category, * usually used for detailed logging) */ Verbose, /** * Prints a verbose message to a log file (if VeryVerbose logging is enabled, * usually used for detailed logging that would otherwise spam output) */ VeryVerbose, // Log masks and special Enum values All = VeryVerbose, NumVerbosity, VerbosityMask = 0xf, SetColor = 0x40, // not actually a verbosity, used to set the color of an output device BreakOnLog = 0x80 };
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