typeface.cpp

/*
 * Copyright 2012 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "gm.h"
#include "sk_tool_utils.h"
#include "Resources.h"
#include "SkCanvas.h"
#include "SkFontStyle.h"
#include "SkString.h"
#include "SkSurfaceProps.h"
#include "SkTypeface.h"
#include "SkTypes.h"

static void getGlyphPositions(const SkPaint& paint, const uint16_t glyphs[],
                             int count, SkScalar x, SkScalar y, SkPoint pos[]) {
    SkASSERT(SkPaint::kGlyphID_TextEncoding == paint.getTextEncoding());

    SkAutoSTMalloc<128, SkScalar> widthStorage(count);
    SkScalar* widths = widthStorage.get();
    paint.getTextWidths(glyphs, count * sizeof(uint16_t), widths);

    for (int i = 0; i < count; ++i) {
        pos[i].set(x, y);
        x += widths[i];
    }
}

static void applyKerning(SkPoint pos[], const int32_t adjustments[], int count,
                         const SkPaint& paint) {
    SkScalar scale = paint.getTextSize() / paint.getTypeface()->getUnitsPerEm();

    SkScalar globalAdj = 0;
    for (int i = 0; i < count - 1; ++i) {
        globalAdj += adjustments[i] * scale;
        pos[i + 1].fX += globalAdj;
    }
}

static void drawKernText(SkCanvas* canvas, const void* text, size_t len,
                         SkScalar x, SkScalar y, const SkPaint& paint) {
    SkTypeface* face = paint.getTypeface();
    if (!face) {
        canvas->drawText(text, len, x, y, paint);
        return;
    }

    SkAutoSTMalloc<128, uint16_t> glyphStorage(len);
    uint16_t* glyphs = glyphStorage.get();
    int glyphCount = paint.textToGlyphs(text, len, glyphs);
    if (glyphCount < 1) {
        return;
    }

    SkAutoSTMalloc<128, int32_t> adjustmentStorage(glyphCount - 1);
    int32_t* adjustments = adjustmentStorage.get();
    if (!face->getKerningPairAdjustments(glyphs, glyphCount, adjustments)) {
        canvas->drawText(text, len, x, y, paint);
        return;
    }

    SkPaint glyphPaint(paint);
    glyphPaint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);

    SkAutoSTMalloc<128, SkPoint> posStorage(glyphCount);
    SkPoint* pos = posStorage.get();
    getGlyphPositions(glyphPaint, glyphs, glyphCount, x, y, pos);

    applyKerning(pos, adjustments, glyphCount, glyphPaint);
    canvas->drawPosText(glyphs, glyphCount * sizeof(uint16_t), pos, glyphPaint);
}

static constexpr SkFontStyle gStyles[] = {
    SkFontStyle::Normal(),
    SkFontStyle::Bold(),
    SkFontStyle::Italic(),
    SkFontStyle::BoldItalic(),
};

constexpr int gStylesCount = SK_ARRAY_COUNT(gStyles);

class TypefaceStylesGM : public skiagm::GM {
    sk_sp<SkTypeface> fFaces[gStylesCount];
    bool fApplyKerning;

public:
    TypefaceStylesGM(bool applyKerning)
        : fApplyKerning(applyKerning) {
        memset(fFaces, 0, sizeof(fFaces));
    }

protected:
    void onOnceBeforeDraw() override {
        for (int i = 0; i < gStylesCount; i++) {
            fFaces[i] = SkTypeface::MakeFromName(nullptr, gStyles[i]);
        }
    }

    SkString onShortName() override {
        SkString name("typefacestyles");
        if (fApplyKerning) {
            name.append("_kerning");
        }
        name.append(sk_tool_utils::platform_font_manager());
        return name;
    }

    SkISize onISize() override {
        return SkISize::Make(640, 480);
    }

    void onDraw(SkCanvas* canvas) override {
        SkPaint paint;
        paint.setAntiAlias(true);
        paint.setTextSize(SkIntToScalar(30));

        const char* text = fApplyKerning ? "Type AWAY" : "Hamburgefons";
        const size_t textLen = strlen(text);

        SkScalar x = SkIntToScalar(10);
        SkScalar dy = paint.getFontMetrics(nullptr);
        SkScalar y = dy;

        if (fApplyKerning) {
            paint.setSubpixelText(true);
        } else {
            paint.setLinearText(true);
        }
        for (int i = 0; i < gStylesCount; i++) {
            paint.setTypeface(fFaces[i]);
            canvas->drawText(text, textLen, x, y, paint);
            if (fApplyKerning) {
                drawKernText(canvas, text, textLen, x + 240, y, paint);
            }
            y += dy;
        }
    }

private:
    typedef skiagm::GM INHERITED;
};

DEF_GM( return new TypefaceStylesGM(false); )
DEF_GM( return new TypefaceStylesGM(true); )

////////////////////////////////////////////////////////////////////////////////

static void draw_typeface_rendering_gm(SkCanvas* canvas, sk_sp<SkTypeface> face,
                                       char character = 'A') {
        struct AliasType {
            bool antiAlias;
            bool subpixelAntitalias;
            bool inLayer;
        } constexpr aliasTypes[] {
#ifndef SK_BUILD_FOR_IOS
            // This gm crashes on iOS when drawing an embedded bitmap when requesting aliased rendering.
            // The crash looks like
            //   libTrueTypeScaler.dylib`<redacted> + 80
            //   stop reason = EXC_BAD_ACCESS (code=EXC_ARM_DA_ALIGN, address=...)
            //   ->  0x330b19d0 <+80>: strd   r2, r3, [r5, #36]
            //       0x330b19d4 <+84>: movs   r3, #0x0
            //       0x330b19d6 <+86>: add    r2, sp, #0x28
            //       0x330b19d8 <+88>: ldr    r0, [r4, #0x4]
            // Disable testing embedded bitmaps on iOS for now.
            // See https://bug.skia.org/5530 .
            { false, false, false },  // aliased
#endif
            { true,  false, false },  // anti-aliased
            { true,  true , false },  // subpixel anti-aliased
            { true,  false, true  },  // anti-aliased in layer (flat pixel geometry)
            { true,  true , true  },  // subpixel anti-aliased in layer (flat pixel geometry)
        };

        // The hintgasp.ttf is designed for the following sizes to be different.
        // GASP_DOGRAY                                      0x0002   0<=ppem<=10
        // GASP_SYMMETRIC_SMOOTHING                         0x0008   0<=ppem<=10
        // GASP_GRIDFIT                                     0x0001  11<=ppem<=12
        // GASP_SYMMETRIC_GRIDFIT                           0x0004  11<=ppem<=12
        // GASP_DOGRAY|GASP_GRIDFIT                         0x0003  13<=ppem<=14
        // GASP_SYMMETRIC_SMOOTHING|GASP_SYMMETRIC_GRIDFIT  0x000C  13<=ppem<=14
        // (neither)                                        0x0000  15<=ppem
        // Odd sizes have embedded bitmaps.
        constexpr SkScalar textSizes[] = { 9, 10, 11, 12, 13, 14, 15, 16 };

        constexpr SkPaint::Hinting hintingTypes[] = { SkPaint::kNo_Hinting,
                                                      SkPaint::kSlight_Hinting,
                                                      SkPaint::kNormal_Hinting,
                                                      SkPaint::kFull_Hinting };

        struct SubpixelType {
            bool requested;
            SkVector offset;
        } constexpr subpixelTypes[] = {
            { false, { 0.00, 0.00 } },
            { true , { 0.00, 0.00 } },
            { true , { 0.25, 0.00 } },
            { true , { 0.25, 0.25 } },
        };

        constexpr bool rotateABitTypes[] = { false, true };

        SkPaint paint;
        paint.setTypeface(face);
        paint.setEmbeddedBitmapText(true);

        SkScalar x = 0;
        SkScalar xMax = x;
        SkScalar xBase = 0;
        SkScalar y = 0;  // The baseline of the previous output
        for (const SubpixelType subpixel : subpixelTypes) {
            y = 0;
            paint.setSubpixelText(subpixel.requested);

            for (const AliasType& alias : aliasTypes) {
                paint.setAntiAlias(alias.antiAlias);
                paint.setLCDRenderText(alias.subpixelAntitalias);
                SkAutoCanvasRestore acr(canvas, false);
                if (alias.inLayer) {
                    canvas->saveLayer(nullptr, &paint);
                }

                for (const SkScalar& textSize : textSizes) {
                    x = xBase + 5;
                    paint.setTextSize(textSize);

                    SkScalar dy = SkScalarCeilToScalar(paint.getFontMetrics(nullptr));
                    y += dy;
                    for (const SkPaint::Hinting& hinting : hintingTypes) {
                        paint.setHinting(hinting);

                        for (const bool& rotateABit : rotateABitTypes) {
                            SkAutoCanvasRestore acr(canvas, true);
                            if (rotateABit) {
                                canvas->rotate(2, x + subpixel.offset.x(),
                                                  y + subpixel.offset.y());
                            }
                            canvas->drawText(&character, 1,
                                             x + subpixel.offset.x(),
                                             y + subpixel.offset.y(), paint);

                            SkScalar dx = SkScalarCeilToScalar(
                                    paint.measureText(&character, 1)) + 5;
                            x += dx;
                            xMax = SkTMax(x, xMax);
                        }
                    }
                }
                y += 10;
            }
            xBase = xMax;
        }
}

DEF_SIMPLE_GM_BG_NAME(typefacerendering, canvas, 640, 680, SK_ColorWHITE,
                      SkStringPrintf("typefacerendering%s",
                                     sk_tool_utils::platform_font_manager())) {
    if (sk_sp<SkTypeface> face = MakeResourceAsTypeface("fonts/hintgasp.ttf")) {
        draw_typeface_rendering_gm(canvas, std::move(face));
    }
}

// Type1 fonts don't currently work in Skia on Windows.
#ifndef SK_BUILD_FOR_WIN

DEF_SIMPLE_GM_BG_NAME(typefacerendering_pfa, canvas, 640, 680, SK_ColorWHITE,
                      SkStringPrintf("typefacerendering_pfa%s",
                                     sk_tool_utils::platform_font_manager())) {
    if (sk_sp<SkTypeface> face = MakeResourceAsTypeface("fonts/Roboto2-Regular.pfa")) {
        // This subsetted typeface doesn't have the character 'A'.
        draw_typeface_rendering_gm(canvas, std::move(face), 'O');
    }
}

DEF_SIMPLE_GM_BG_NAME(typefacerendering_pfb, canvas, 640, 680, SK_ColorWHITE,
                      SkStringPrintf("typefacerendering_pfb%s",
                                     sk_tool_utils::platform_font_manager())) {
    if (sk_sp<SkTypeface> face = MakeResourceAsTypeface("fonts/Roboto2-Regular.pfb")) {
        draw_typeface_rendering_gm(canvas, std::move(face), 'O');
    }
}

#endif