UE入门教程06.03：读取本地文件为纹理并显示

系列索引：UE入门教程索引

基于UE入门教程06.02：创建插件继续操作。

目的

本文介绍如何从本地读取图片，转换为纹理，然后显示到界面上。

工程

和上一篇一样，直接拿过来就可以了。

插件

模块

找到*.Build.cs，找到

1	`PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore"});`

添加新模块，此模块用于读取图片

1	`PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore" ,"ImageWrapper"});`

头文件

添加头文件

#include "Engine/Texture2D.h"
#include "Runtime/Core/Public/Misc/Paths.h"
#include "Runtime/ImageWrapper/Public/IImageWrapper.h"
#include "Runtime/ImageWrapper/Public/IImageWrapperModule.h"
#include "Core\Public\HAL\UnrealMemory.h"
#include "Core\Public\HAL\FileManagerGeneric.h"
#include "Core\Public\HAL\FileManager.h"
#include "Core\Public\Misc\FileHelper.h"

声明

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GENERATED_BODY()
	UFUNCTION(BlueprintCallable, Category = "MyFun")
	static UTexture2D* LoadTexture2D(const FString path, bool& IsValid, int32& OutWidth, int32& OutHeight);

实现

static IImageWrapperPtr GetImageWrapperByExtention(const FString InImagePath)
{
    IImageWrapperModule& ImageWrapperModule = FModuleManager::LoadModuleChecked<IImageWrapperModule>(FName("ImageWrapper"));
    if (InImagePath.EndsWith(".png"))
    {
        return ImageWrapperModule.CreateImageWrapper(EImageFormat::PNG);
    }
    else if (InImagePath.EndsWith(".jpg") || InImagePath.EndsWith(".jpeg"))
    {
        return ImageWrapperModule.CreateImageWrapper(EImageFormat::JPEG);
    }
    else if (InImagePath.EndsWith(".bmp"))
    {
        return ImageWrapperModule.CreateImageWrapper(EImageFormat::BMP);
    }
    else if (InImagePath.EndsWith(".ico"))
    {
        return ImageWrapperModule.CreateImageWrapper(EImageFormat::ICO);
    }
    else if (InImagePath.EndsWith("exr"))
    {
        return ImageWrapperModule.CreateImageWrapper(EImageFormat::EXR);
    }
    else if (InImagePath.EndsWith(".icns"))
    {
        return ImageWrapperModule.CreateImageWrapper(EImageFormat::ICNS);
    }
    return nullptr;
}

UTexture2D* UMyBlueprintFunctionLibrary::LoadTexture2D(const FString path, bool& IsValid, int32& OutWidth, int32& OutHeight)
{
    UTexture2D* Texture = nullptr;
    IsValid = false;
    if (!FPlatformFileManager::Get().GetPlatformFile().FileExists(*path))
    {
        return nullptr;
    }
    TArray<uint8> RawFileData;
    if (!FFileHelper::LoadFileToArray(RawFileData, *path))
    {
        return nullptr;
    }
    IImageWrapperPtr ImageWrapper = GetImageWrapperByExtention(path);
    if (ImageWrapper.IsValid() && ImageWrapper->SetCompressed(RawFileData.GetData(), RawFileData.Num()))
    {
        TArray<uint8> UncompressedRGBA;
        if (ImageWrapper->GetRaw(ERGBFormat::RGBA, 8, UncompressedRGBA))
        {
            Texture = UTexture2D::CreateTransient(ImageWrapper->GetWidth(), ImageWrapper->GetHeight(), PF_R8G8B8A8);
            if (Texture != nullptr)
            {
                IsValid = true;
                OutWidth = ImageWrapper->GetWidth();
                OutHeight = ImageWrapper->GetHeight();
                void* TextureData = Texture->PlatformData->Mips[0].BulkData.Lock(LOCK_READ_WRITE);
                FMemory::Memcpy(TextureData, UncompressedRGBA.GetData(), UncompressedRGBA.Num());
                Texture->PlatformData->Mips[0].BulkData.Unlock();
                Texture->UpdateResource();
            }
        }
    }
    return Texture;
}