SkPDFShader.cpp File Reference

#include "src/pdf/SkPDFShader.h"
#include "include/core/SkData.h"
#include "include/core/SkScalar.h"
#include "include/core/SkStream.h"
#include "include/core/SkSurface.h"
#include "include/core/SkTileMode.h"
#include "include/docs/SkPDFDocument.h"
#include "include/private/base/SkMath.h"
#include "include/private/base/SkTPin.h"
#include "include/private/base/SkTemplates.h"
#include "src/pdf/SkPDFDevice.h"
#include "src/pdf/SkPDFDocumentPriv.h"
#include "src/pdf/SkPDFFormXObject.h"
#include "src/pdf/SkPDFGradientShader.h"
#include "src/pdf/SkPDFGraphicState.h"
#include "src/pdf/SkPDFResourceDict.h"
#include "src/pdf/SkPDFUtils.h"

Go to the source code of this file.

Functions
static void	draw (SkCanvas *canvas, const SkImage *image, SkColor4f paintColor)
static SkBitmap	to_bitmap (const SkImage *image)
static void	draw_matrix (SkCanvas *canvas, const SkImage *image, const SkMatrix &matrix, SkColor4f paintColor)
static void	draw_bitmap_matrix (SkCanvas *canvas, const SkBitmap &bm, const SkMatrix &matrix, SkColor4f paintColor)
static void	fill_color_from_bitmap (SkCanvas *canvas, float left, float top, float right, float bottom, const SkBitmap &bitmap, int x, int y, float alpha)
static SkMatrix	scale_translate (SkScalar sx, SkScalar sy, SkScalar tx, SkScalar ty)
static bool	is_tiled (SkTileMode m)
static SkPDFIndirectReference	make_image_shader (SkPDFDocument *doc, SkMatrix finalMatrix, SkTileMode tileModesX, SkTileMode tileModesY, SkRect bBox, const SkImage *image, SkColor4f paintColor)
static SkPDFIndirectReference	make_fallback_shader (SkPDFDocument *doc, SkShader *shader, const SkMatrix &canvasTransform, const SkIRect &surfaceBBox, SkColor4f paintColor)
static SkColor4f	adjust_color (SkShader *shader, SkColor4f paintColor)
SkPDFIndirectReference	SkPDFMakeShader (SkPDFDocument *doc, SkShader *shader, const SkMatrix &canvasTransform, const SkIRect &surfaceBBox, SkColor4f paintColor)

Function Documentation

adjust_color()

static SkColor4f adjust_color ( SkShader *  shader, SkColor4f  paintColor  )

static

Definition at line 316 of file SkPDFShader.cpp.

                                                                      {
    if (SkImage* img = shader->isAImage(nullptr, (SkTileMode*)nullptr)) {
        if (img->isAlphaOnly()) {
            return paintColor;
        }
    }
    return SkColor4f{0, 0, 0, paintColor.fA};  // only preserve the alpha.
}

draw()

static void draw ( SkCanvas *  canvas, const SkImage *  image, SkColor4f  paintColor  )

static

Definition at line 27 of file SkPDFShader.cpp.

                                                                               {
    SkPaint paint(paintColor);
    canvas->drawImage(image, 0, 0, SkSamplingOptions(), &paint);
}

draw_bitmap_matrix()

static void draw_bitmap_matrix ( SkCanvas *  canvas, const SkBitmap &  bm, const SkMatrix &  matrix, SkColor4f  paintColor  )

static

Definition at line 48 of file SkPDFShader.cpp.

                                                                             {
    SkAutoCanvasRestore acr(canvas, true);
    canvas->concat(matrix);
    SkPaint paint(paintColor);
    canvas->drawImage(bm.asImage(), 0, 0, SkSamplingOptions(), &paint);
}

draw_matrix()

static void draw_matrix ( SkCanvas *  canvas, const SkImage *  image, const SkMatrix &  matrix, SkColor4f  paintColor  )

static

Definition at line 41 of file SkPDFShader.cpp.

                                                                      {
    SkAutoCanvasRestore acr(canvas, true);
    canvas->concat(matrix);
    draw(canvas, image, paintColor);
}

fill_color_from_bitmap()

static void fill_color_from_bitmap ( SkCanvas *  canvas, float  left, float  top, float  right, float  bottom, const SkBitmap &  bitmap, int  x, int  y, float  alpha  )

static

Definition at line 56 of file SkPDFShader.cpp.

                                                                                      {
    SkRect rect{left, top, right, bottom};
    if (!rect.isEmpty()) {
        SkColor4f color = SkColor4f::FromColor(bitmap.getColor(x, y));
        SkPaint paint(SkColor4f{color.fR, color.fG, color.fB, alpha * color.fA});
        canvas->drawRect(rect, paint);
    }
}

is_tiled()

static bool is_tiled ( SkTileMode  m )

static

Definition at line 73 of file SkPDFShader.cpp.

{ return SkTileMode::kMirror == m || SkTileMode::kRepeat == m; }

make_fallback_shader()

static SkPDFIndirectReference make_fallback_shader ( SkPDFDocument *  doc, SkShader *  shader, const SkMatrix &  canvasTransform, const SkIRect &  surfaceBBox, SkColor4f  paintColor  )

static

Definition at line 264 of file SkPDFShader.cpp.

                                                                         {
    // surfaceBBox is in device space. While that's exactly what we
    // want for sizing our bitmap, we need to map it into
    // shader space for adjustments (to match
    // MakeImageShader's behavior).
    SkRect shaderRect = SkRect::Make(surfaceBBox);
    if (!SkPDFUtils::InverseTransformBBox(canvasTransform, &shaderRect)) {
        return SkPDFIndirectReference();
    }
    // Clamp the bitmap size to about 1M pixels
    static const int kMaxBitmapArea = 1024 * 1024;
    SkScalar bitmapArea = (float)surfaceBBox.width() * (float)surfaceBBox.height();
    SkScalar rasterScale = 1.0f;
    if (bitmapArea > (float)kMaxBitmapArea) {
        rasterScale *= SkScalarSqrt((float)kMaxBitmapArea / bitmapArea);
    }
 
    SkISize size = {
        SkTPin(SkScalarCeilToInt(rasterScale * surfaceBBox.width()),  1, kMaxBitmapArea),
        SkTPin(SkScalarCeilToInt(rasterScale * surfaceBBox.height()), 1, kMaxBitmapArea)};
    SkSize scale = {SkIntToScalar(size.width()) / shaderRect.width(),
                    SkIntToScalar(size.height()) / shaderRect.height()};
 
    auto surface = SkSurfaces::Raster(SkImageInfo::MakeN32Premul(size.width(), size.height()));
    SkASSERT(surface);
    SkCanvas* canvas = surface->getCanvas();
    canvas->clear(SK_ColorTRANSPARENT);
 
    SkPaint p(paintColor);
    p.setShader(sk_ref_sp(shader));
 
    canvas->scale(scale.width(), scale.height());
    canvas->translate(-shaderRect.x(), -shaderRect.y());
    canvas->drawPaint(p);
 
    auto shaderTransform = SkMatrix::Translate(shaderRect.x(), shaderRect.y());
    shaderTransform.preScale(1 / scale.width(), 1 / scale.height());
 
    sk_sp<SkImage> image = surface->makeImageSnapshot();
    SkASSERT(image);
    return make_image_shader(doc,
                             SkMatrix::Concat(canvasTransform, shaderTransform),
                             SkTileMode::kClamp, SkTileMode::kClamp,
                             SkRect::Make(surfaceBBox),
                             image.get(),
                             paintColor);
}

make_image_shader()

static SkPDFIndirectReference make_image_shader ( SkPDFDocument *  doc, SkMatrix  finalMatrix, SkTileMode  tileModesX, SkTileMode  tileModesY, SkRect  bBox, const SkImage *  image, SkColor4f  paintColor  )

static

Definition at line 75 of file SkPDFShader.cpp.

                                                                      {
    // The image shader pattern cell will be drawn into a separate device
    // in pattern cell space (no scaling on the bitmap, though there may be
    // translations so that all content is in the device, coordinates > 0).
 
    // Map clip bounds to shader space to ensure the device is large enough
    // to handle fake clamping.
 
    SkRect deviceBounds = bBox;
    if (!SkPDFUtils::InverseTransformBBox(finalMatrix, &deviceBounds)) {
        return SkPDFIndirectReference();
    }
 
    SkRect bitmapBounds = SkRect::MakeSize(SkSize::Make(image->dimensions()));
 
    // For tiling modes, the bounds should be extended to include the bitmap,
    // otherwise the bitmap gets clipped out and the shader is empty and awful.
    // For clamp modes, we're only interested in the clip region, whether
    // or not the main bitmap is in it.
    if (is_tiled(tileModesX) || is_tiled(tileModesY)) {
        deviceBounds.join(bitmapBounds);
    }
 
    SkISize patternDeviceSize = {SkScalarCeilToInt(deviceBounds.width()),
                                 SkScalarCeilToInt(deviceBounds.height())};
    auto patternDevice = sk_make_sp<SkPDFDevice>(patternDeviceSize, doc);
    SkCanvas canvas(patternDevice);
 
    SkRect patternBBox = SkRect::MakeSize(SkSize::Make(image->dimensions()));
    SkScalar width = patternBBox.width();
    SkScalar height = patternBBox.height();
 
    // Translate the canvas so that the bitmap origin is at (0, 0).
    canvas.translate(-deviceBounds.left(), -deviceBounds.top());
    patternBBox.offset(-deviceBounds.left(), -deviceBounds.top());
    // Undo the translation in the final matrix
    finalMatrix.preTranslate(deviceBounds.left(), deviceBounds.top());
 
    // If the bitmap is out of bounds (i.e. clamp mode where we only see the
    // stretched sides), canvas will clip this out and the extraneous data
    // won't be saved to the PDF.
    draw(&canvas, image, paintColor);
 
    // Tiling is implied.  First we handle mirroring.
    if (tileModesX == SkTileMode::kMirror) {
        draw_matrix(&canvas, image, scale_translate(-1, 1, 2 * width, 0), paintColor);
        patternBBox.fRight += width;
    }
    if (tileModesY == SkTileMode::kMirror) {
        draw_matrix(&canvas, image, scale_translate(1, -1, 0, 2 * height), paintColor);
        patternBBox.fBottom += height;
    }
    if (tileModesX == SkTileMode::kMirror && tileModesY == SkTileMode::kMirror) {
        draw_matrix(&canvas, image, scale_translate(-1, -1, 2 * width, 2 * height), paintColor);
    }
 
    // Then handle Clamping, which requires expanding the pattern canvas to
    // cover the entire surfaceBBox.
 
    SkBitmap bitmap;
    if (tileModesX == SkTileMode::kClamp || tileModesY == SkTileMode::kClamp) {
        // For now, the easiest way to access the colors in the corners and sides is
        // to just make a bitmap from the image.
        bitmap = to_bitmap(image);
    }
 
    // If both x and y are in clamp mode, we start by filling in the corners.
    // (Which are just a rectangles of the corner colors.)
    if (tileModesX == SkTileMode::kClamp && tileModesY == SkTileMode::kClamp) {
        SkASSERT(!bitmap.drawsNothing());
 
        fill_color_from_bitmap(&canvas, deviceBounds.left(), deviceBounds.top(), 0, 0,
                               bitmap, 0, 0, paintColor.fA);
 
        fill_color_from_bitmap(&canvas, width, deviceBounds.top(), deviceBounds.right(), 0,
                               bitmap, bitmap.width() - 1, 0, paintColor.fA);
 
        fill_color_from_bitmap(&canvas, width, height, deviceBounds.right(), deviceBounds.bottom(),
                               bitmap, bitmap.width() - 1, bitmap.height() - 1, paintColor.fA);
 
        fill_color_from_bitmap(&canvas, deviceBounds.left(), height, 0, deviceBounds.bottom(),
                               bitmap, 0, bitmap.height() - 1, paintColor.fA);
    }
 
    // Then expand the left, right, top, then bottom.
    if (tileModesX == SkTileMode::kClamp) {
        SkASSERT(!bitmap.drawsNothing());
        SkIRect subset = SkIRect::MakeXYWH(0, 0, 1, bitmap.height());
        if (deviceBounds.left() < 0) {
            SkBitmap left;
            SkAssertResult(bitmap.extractSubset(&left, subset));
 
            SkMatrix leftMatrix = scale_translate(-deviceBounds.left(), 1, deviceBounds.left(), 0);
            draw_bitmap_matrix(&canvas, left, leftMatrix, paintColor);
 
            if (tileModesY == SkTileMode::kMirror) {
                leftMatrix.postScale(SK_Scalar1, -SK_Scalar1);
                leftMatrix.postTranslate(0, 2 * height);
                draw_bitmap_matrix(&canvas, left, leftMatrix, paintColor);
            }
            patternBBox.fLeft = 0;
        }
 
        if (deviceBounds.right() > width) {
            SkBitmap right;
            subset.offset(bitmap.width() - 1, 0);
            SkAssertResult(bitmap.extractSubset(&right, subset));
 
            SkMatrix rightMatrix = scale_translate(deviceBounds.right() - width, 1, width, 0);
            draw_bitmap_matrix(&canvas, right, rightMatrix, paintColor);
 
            if (tileModesY == SkTileMode::kMirror) {
                rightMatrix.postScale(SK_Scalar1, -SK_Scalar1);
                rightMatrix.postTranslate(0, 2 * height);
                draw_bitmap_matrix(&canvas, right, rightMatrix, paintColor);
            }
            patternBBox.fRight = deviceBounds.width();
        }
    }
    if (tileModesX == SkTileMode::kDecal) {
        if (deviceBounds.left() < 0) {
            patternBBox.fLeft = 0;
        }
        if (deviceBounds.right() > width) {
            patternBBox.fRight = deviceBounds.width();
        }
    }
 
    if (tileModesY == SkTileMode::kClamp) {
        SkASSERT(!bitmap.drawsNothing());
        SkIRect subset = SkIRect::MakeXYWH(0, 0, bitmap.width(), 1);
        if (deviceBounds.top() < 0) {
            SkBitmap top;
            SkAssertResult(bitmap.extractSubset(&top, subset));
 
            SkMatrix topMatrix = scale_translate(1, -deviceBounds.top(), 0, deviceBounds.top());
            draw_bitmap_matrix(&canvas, top, topMatrix, paintColor);
 
            if (tileModesX == SkTileMode::kMirror) {
                topMatrix.postScale(-1, 1);
                topMatrix.postTranslate(2 * width, 0);
                draw_bitmap_matrix(&canvas, top, topMatrix, paintColor);
            }
            patternBBox.fTop = 0;
        }
 
        if (deviceBounds.bottom() > height) {
            SkBitmap bottom;
            subset.offset(0, bitmap.height() - 1);
            SkAssertResult(bitmap.extractSubset(&bottom, subset));
 
            SkMatrix bottomMatrix = scale_translate(1, deviceBounds.bottom() - height, 0, height);
            draw_bitmap_matrix(&canvas, bottom, bottomMatrix, paintColor);
 
            if (tileModesX == SkTileMode::kMirror) {
                bottomMatrix.postScale(-1, 1);
                bottomMatrix.postTranslate(2 * width, 0);
                draw_bitmap_matrix(&canvas, bottom, bottomMatrix, paintColor);
            }
            patternBBox.fBottom = deviceBounds.height();
        }
    }
    if (tileModesY == SkTileMode::kDecal) {
        if (deviceBounds.top() < 0) {
            patternBBox.fTop = 0;
        }
        if (deviceBounds.bottom() > height) {
            patternBBox.fBottom = deviceBounds.height();
        }
    }
 
    auto imageShader = patternDevice->content();
    std::unique_ptr<SkPDFDict> resourceDict = patternDevice->makeResourceDict();
    std::unique_ptr<SkPDFDict> dict = SkPDFMakeDict();
    SkPDFUtils::PopulateTilingPatternDict(dict.get(), patternBBox,
                                          std::move(resourceDict), finalMatrix);
    return SkPDFStreamOut(std::move(dict), std::move(imageShader), doc);
}

scale_translate()

static SkMatrix scale_translate ( SkScalar  sx, SkScalar  sy, SkScalar  tx, SkScalar  ty  )

static

Definition at line 67 of file SkPDFShader.cpp.

                                                                                    {
    SkMatrix m;
    m.setScaleTranslate(sx, sy, tx, ty);
    return m;
}

SkPDFMakeShader()

SkPDFIndirectReference SkPDFMakeShader	(	SkPDFDocument *	doc,
		SkShader *	shader,
		const SkMatrix &	ctm,
		const SkIRect &	surfaceBBox,
		SkColor4f	paintColor
	)

Make a PDF shader for the passed SkShader. If the SkShader is invalid in some way, returns nullptr.

In PDF parlance, this is a pattern, used in place of a color when the pattern color space is selected.

May cache the shader in the document for later re-use. If this function is called again with an equivalent shader, a new reference to the cached pdf shader may be returned.

Parameters

doc	The parent document, must be non-null.
shader	The SkShader to emulate.
ctm	The current transform matrix. (PDF shaders are absolutely positioned, relative to where the page is drawn.)
surfaceBBox	The bounding box of the drawing surface (with matrix already applied).
paintColor	Color+Alpha of the paint. Color is usually ignored, unless it is a alpha shader.

Definition at line 325 of file SkPDFShader.cpp.

                                                             {
    SkASSERT(shader);
    SkASSERT(doc);
    if (as_SB(shader)->asGradient() != SkShaderBase::GradientType::kNone) {
        return SkPDFGradientShader::Make(doc, shader, canvasTransform, surfaceBBox);
    }
    if (surfaceBBox.isEmpty()) {
        return SkPDFIndirectReference();
    }
    SkBitmap image;
 
    paintColor = adjust_color(shader, paintColor);
    SkMatrix shaderTransform;
    SkTileMode imageTileModes[2];
    if (SkImage* skimg = shader->isAImage(&shaderTransform, imageTileModes)) {
        SkMatrix finalMatrix = SkMatrix::Concat(canvasTransform, shaderTransform);
        SkPDFImageShaderKey key = {
            finalMatrix,
            surfaceBBox,
            SkBitmapKeyFromImage(skimg),
            {imageTileModes[0], imageTileModes[1]},
            paintColor};
        SkPDFIndirectReference* shaderPtr = doc->fImageShaderMap.find(key);
        if (shaderPtr) {
            return *shaderPtr;
        }
        SkPDFIndirectReference pdfShader =
                make_image_shader(doc,
                                  finalMatrix,
                                  imageTileModes[0],
                                  imageTileModes[1],
                                  SkRect::Make(surfaceBBox),
                                  skimg,
                                  paintColor);
        doc->fImageShaderMap.set(std::move(key), pdfShader);
        return pdfShader;
    }
    // Don't bother to de-dup fallback shader.
    return make_fallback_shader(doc, shader, canvasTransform, surfaceBBox, paintColor);
}

to_bitmap()

static SkBitmap to_bitmap ( const SkImage *  image )

static

Definition at line 32 of file SkPDFShader.cpp.

                                                {
    SkBitmap bitmap;
    if (!SkPDFUtils::ToBitmap(image, &bitmap)) {
        bitmap.allocN32Pixels(image->width(), image->height());
        bitmap.eraseColor(0x00000000);
    }
    return bitmap;
}