MinikinUtils.cpp revision 63c5c78a72a21d57913e8601cc2a1ab72a424a02 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define LOG_TAG "Minikin"
18#include <cutils/log.h>
19#include <string>
20
21#include "SkPathMeasure.h"
22#include "minikin/Layout.h"
23#include "Paint.h"
24#include "TypefaceImpl.h"
25#include "MinikinSkia.h"
26
27#include "MinikinUtils.h"
28
29namespace android {
30
31// Do an sprintf starting at offset n, abort on overflow
32static int snprintfcat(char* buf, int off, int size, const char* format, ...)
33        __attribute__((__format__(__printf__, 4, 5)));
34static int snprintfcat(char* buf, int off, int size, const char* format, ...) {
35    va_list args;
36    va_start(args, format);
37    int n = vsnprintf(buf + off, size - off, format, args);
38    LOG_ALWAYS_FATAL_IF(n >= size - off, "String overflow in setting layout properties");
39    va_end(args);
40    return off + n;
41}
42
43void MinikinUtils::doLayout(Layout* layout, const Paint* paint, int bidiFlags, TypefaceImpl* typeface,
44        const uint16_t* buf, size_t start, size_t count, size_t bufSize) {
45    TypefaceImpl* resolvedFace = TypefaceImpl_resolveDefault(typeface);
46    layout->setFontCollection(resolvedFace->fFontCollection);
47    FontStyle style = resolvedFace->fStyle;
48    char css[512];
49    int off = snprintfcat(css, 0, sizeof(css),
50        "font-size: %d; font-scale-x: %f; font-skew-x: %f; -paint-flags: %d;"
51        " font-weight: %d; font-style: %s; -minikin-bidi: %d; letter-spacing: %f;",
52        (int)paint->getTextSize(),
53        paint->getTextScaleX(),
54        paint->getTextSkewX(),
55        MinikinFontSkia::packPaintFlags(paint),
56        style.getWeight() * 100,
57        style.getItalic() ? "italic" : "normal",
58        bidiFlags,
59        paint->getLetterSpacing());
60    SkString langString = paint->getPaintOptionsAndroid().getLanguage().getTag();
61    off = snprintfcat(css, off, sizeof(css), " lang: %s;", langString.c_str());
62    SkPaintOptionsAndroid::FontVariant var = paint->getPaintOptionsAndroid().getFontVariant();
63    const char* varstr = var == SkPaintOptionsAndroid::kElegant_Variant ? "elegant" : "compact";
64    off = snprintfcat(css, off, sizeof(css), " -minikin-variant: %s;", varstr);
65    layout->doLayout(buf, start, count, bufSize, std::string(css));
66}
67
68float MinikinUtils::xOffsetForTextAlign(Paint* paint, const Layout& layout) {
69    switch (paint->getTextAlign()) {
70        case Paint::kCenter_Align:
71            return layout.getAdvance() * -0.5f;
72            break;
73        case Paint::kRight_Align:
74            return -layout.getAdvance();
75            break;
76        default:
77            break;
78    }
79    return 0;
80}
81
82float MinikinUtils::hOffsetForTextAlign(Paint* paint, const Layout& layout, const SkPath& path) {
83    float align = 0;
84    switch (paint->getTextAlign()) {
85        case Paint::kCenter_Align:
86            align = -0.5f;
87            break;
88        case Paint::kRight_Align:
89            align = -1;
90            break;
91        default:
92            return 0;
93    }
94    SkPathMeasure measure(path, false);
95    return align * (layout.getAdvance() - measure.getLength());
96}
97
98}
99