Magpie/MODULE_Common/PixelScaleTransform.h

#pragma once
#include "pch.h"
#include <SimpleDrawTransform.h>
#include "EffectDefines.h"


class PixelScaleTransform : public SimpleDrawTransform<> {
protected:
	PixelScaleTransform() : SimpleDrawTransform<>(GUID_MAGPIE_PIXEL_SCALE_SHADER) {}

public:
	virtual ~PixelScaleTransform() {}

	static HRESULT Create(
		_In_ ID2D1EffectContext* d2dEC,
		_Outptr_ PixelScaleTransform** ppOutput
	) {
		if (!ppOutput) {
			return E_INVALIDARG;
		}

		HRESULT hr = LoadShader(d2dEC, MAGPIE_PIXEL_SCALE_SHADER, GUID_MAGPIE_PIXEL_SCALE_SHADER);
		if (FAILED(hr)) {
			return hr;
		}

		*ppOutput = new PixelScaleTransform();
		return S_OK;
	}

	void SetScale(int scale) {
		assert(scale > 0);
		_scale = scale;
	}

	int GetScale() const {
		return _scale;
	}

	IFACEMETHODIMP MapInputRectsToOutputRect(
		_In_reads_(inputRectCount) const D2D1_RECT_L* pInputRects,
		_In_reads_(inputRectCount) const D2D1_RECT_L* pInputOpaqueSubRects,
		UINT32 inputRectCount,
		_Out_ D2D1_RECT_L* pOutputRect,
		_Out_ D2D1_RECT_L* pOutputOpaqueSubRect
	) override {
		if (inputRectCount != 1) {
			return E_INVALIDARG;
		}

		_inputRects[0] = pInputRects[0];

		SIZE srcSize = { _inputRects[0].right - _inputRects[0].left,_inputRects[0].bottom - _inputRects[0].top };
		SIZE destSize = {
			srcSize.cx * _scale,
			srcSize.cy * _scale
		};

		*pOutputRect = { 0, 0, destSize.cx, destSize.cy };
		*pOutputOpaqueSubRect = {};

		_SetShaderConstantBuffer(srcSize);

		return S_OK;
	}

protected:
	void _SetShaderConstantBuffer(const SIZE& srcSize) override {
		struct {
			INT32 srcWidth;
			INT32 srcHeight;
			INT32 scale;
		} shaderConstants{
			srcSize.cx,
			srcSize.cy,
			_scale
		};

		_drawInfo->SetPixelShaderConstantBuffer((BYTE*)&shaderConstants, sizeof(shaderConstants));
	}

private:
	// 缩放倍数
	int _scale = 1;
};