gecko-dev/dom/canvas/CanvasUtils.h

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef _CANVASUTILS_H_
#define _CANVASUTILS_H_

#include "CanvasRenderingContextHelper.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/dom/ToJSValue.h"
#include "jsapi.h"
#include "mozilla/FloatingPoint.h"

class nsIPrincipal;

namespace mozilla {

namespace dom {
class HTMLCanvasElement;
}  // namespace dom

namespace CanvasUtils {

bool GetCanvasContextType(const nsAString& str,
                          dom::CanvasContextType* const out_type);

// Check that the rectangle [x,y,w,h] is a subrectangle of
// [0,0,realWidth,realHeight]

inline bool CheckSaneSubrectSize(int32_t x, int32_t y, int32_t w, int32_t h,
                                 int32_t realWidth, int32_t realHeight) {
  CheckedInt32 checked_xmost = CheckedInt32(x) + w;
  CheckedInt32 checked_ymost = CheckedInt32(y) + h;

  return w >= 0 && h >= 0 && x >= 0 && y >= 0 && checked_xmost.isValid() &&
         checked_xmost.value() <= realWidth && checked_ymost.isValid() &&
         checked_ymost.value() <= realHeight;
}

// Flag aCanvasElement as write-only if drawing an image with aPrincipal
// onto it would make it such.

void DoDrawImageSecurityCheck(dom::HTMLCanvasElement* aCanvasElement,
                              nsIPrincipal* aPrincipal, bool forceWriteOnly,
                              bool CORSUsed);

// Check if the context is chrome or has the permission to drawWindow
bool HasDrawWindowPrivilege(JSContext* aCx, JSObject* aObj);

// Check site-specific permission and display prompt if appropriate.
bool IsImageExtractionAllowed(nsIDocument* aDocument, JSContext* aCx,
                              nsIPrincipal& aPrincipal);

// Make a double out of |v|, treating undefined values as 0.0 (for
// the sake of sparse arrays).  Return true iff coercion
// succeeded.
bool CoerceDouble(const JS::Value& v, double* d);

/* Float validation stuff */
#define VALIDATE(_f) \
  if (!IsFinite(_f)) return false

inline bool FloatValidate(double f1) {
  VALIDATE(f1);
  return true;
}

inline bool FloatValidate(double f1, double f2) {
  VALIDATE(f1);
  VALIDATE(f2);
  return true;
}

inline bool FloatValidate(double f1, double f2, double f3) {
  VALIDATE(f1);
  VALIDATE(f2);
  VALIDATE(f3);
  return true;
}

inline bool FloatValidate(double f1, double f2, double f3, double f4) {
  VALIDATE(f1);
  VALIDATE(f2);
  VALIDATE(f3);
  VALIDATE(f4);
  return true;
}

inline bool FloatValidate(double f1, double f2, double f3, double f4,
                          double f5) {
  VALIDATE(f1);
  VALIDATE(f2);
  VALIDATE(f3);
  VALIDATE(f4);
  VALIDATE(f5);
  return true;
}

inline bool FloatValidate(double f1, double f2, double f3, double f4, double f5,
                          double f6) {
  VALIDATE(f1);
  VALIDATE(f2);
  VALIDATE(f3);
  VALIDATE(f4);
  VALIDATE(f5);
  VALIDATE(f6);
  return true;
}

#undef VALIDATE

template <typename T>
nsresult JSValToDashArray(JSContext* cx, const JS::Value& patternArray,
                          nsTArray<T>& dashes) {
  // The cap is pretty arbitrary.  16k should be enough for
  // anybody...
  static const uint32_t MAX_NUM_DASHES = 1 << 14;

  if (!patternArray.isPrimitive()) {
    JS::Rooted<JSObject*> obj(cx, patternArray.toObjectOrNull());
    uint32_t length;
    if (!JS_GetArrayLength(cx, obj, &length)) {
      // Not an array-like thing
      return NS_ERROR_INVALID_ARG;
    } else if (length > MAX_NUM_DASHES) {
      // Too many dashes in the pattern
      return NS_ERROR_ILLEGAL_VALUE;
    }

    bool haveNonzeroElement = false;
    for (uint32_t i = 0; i < length; ++i) {
      JS::Rooted<JS::Value> elt(cx);
      double d;
      if (!JS_GetElement(cx, obj, i, &elt)) {
        return NS_ERROR_FAILURE;
      }
      if (!(CoerceDouble(elt, &d) && FloatValidate(d) && d >= 0.0)) {
        // Pattern elements must be finite "numbers" >= 0.
        return NS_ERROR_INVALID_ARG;
      } else if (d > 0.0) {
        haveNonzeroElement = true;
      }
      if (!dashes.AppendElement(d, mozilla::fallible)) {
        return NS_ERROR_OUT_OF_MEMORY;
      }
    }

    if (dashes.Length() > 0 && !haveNonzeroElement) {
      // An all-zero pattern makes no sense.
      return NS_ERROR_ILLEGAL_VALUE;
    }
  } else if (!(patternArray.isUndefined() || patternArray.isNull())) {
    // undefined and null mean "reset to no dash".  Any other
    // random garbage is a type error.
    return NS_ERROR_INVALID_ARG;
  }

  return NS_OK;
}

template <typename T>
void DashArrayToJSVal(nsTArray<T>& dashes, JSContext* cx,
                      JS::MutableHandle<JS::Value> retval,
                      mozilla::ErrorResult& rv) {
  if (dashes.IsEmpty()) {
    retval.setNull();
    return;
  }
  JS::Rooted<JS::Value> val(cx);
  if (!mozilla::dom::ToJSValue(cx, dashes, retval)) {
    rv.Throw(NS_ERROR_OUT_OF_MEMORY);
  }
}

}  // namespace CanvasUtils
}  // namespace mozilla

#endif /* _CANVASUTILS_H_ */