Image doesn't fill its parent

I tried to load image as decoration for parent container but had the same result. I also couldn't find a way to load svg to decoration, so I stopped at Stack.

Here is my code:

class MainPageViewItem extends StatelessWidget {
  final mainPageViewItem;

  MainPageViewItem(this.mainPageViewItem);

  @override
  Widget build(BuildContext context) {
    return Container(
      margin: EdgeInsets.symmetric(horizontal: 10),
      height: 150,
      child: Stack(
        children: <Widget>[
          Column (
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              Container(
                child: Text(
                  'some text',
                  style: TextStyle(
                      fontSize: 16,
                      fontWeight: FontWeight.w500,
                      color: Color(0xFFFFFFFF),
                      letterSpacing: 0.0015
                  ),
                ),
                margin: EdgeInsets.fromLTRB(40, 30, 12, 0),
              ),
              Container(
                child: Text(
                  'some text',
                  style: MyTextStyles.bodyLightTextStyle,
                ),
                margin: EdgeInsets.fromLTRB(40, 20, 12, 15),
              ),
            ],
          ),
          SvgPicture.asset(
              'assets/vectors/wave_mask.svg',
              fit: BoxFit.fill,
          ),
        ],
      ),
      decoration: BoxDecoration(
          gradient: LinearGradient(
              colors: <Color> [
                mainPageViewItem.startColor,
                mainPageViewItem.endColor
              ],
              begin: Alignment.bottomLeft,
              end: Alignment.topRight,
          ),
          borderRadius: BorderRadius.all(Radius.circular(4.0))
      ),
    );
  }
}

And here is result:

UPDATE: xml code of "wave mask" svg:

<svg width="328" height="152" viewBox="0 0 328 152" fill="none" xmlns="http://www.w3.org/2000/svg">
<mask id="mask0" mask-type="alpha" maskUnits="userSpaceOnUse" x="16" y="12" width="296" height="120">
<rect x="16" y="12" width="296" height="120" fill="url(#paint0_linear)"/>
</mask>
<g mask="url(#mask0)">
<path style="mix-blend-mode:overlay" opacity="0.25" d="M382.842 52.5C345.722 18.362 283.573 16.5 204.531 33.472C125.488 50.4441 105.488 -10.8214 71.9514 -82C38.6146 -152.757 179.945 -77.9483 179.945 -77.9483L272.883 -96.484L382.842 52.5Z" fill="url(#paint1_linear)"/>
<g style="mix-blend-mode:overlay" opacity="0.3">
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M-157.854 115.272C-44.2231 46.1702 64.6931 171.165 149.576 173.141C271.902 176.011 297.826 54.1459 360.305 106.524C422.784 158.902 481.373 204.464 533.973 116.2C586.572 27.936 639.405 72.3972 639.405 72.3972" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.405 73.9629C638.689 74.2268 584.552 28.7079 531.802 115.603C479.052 202.498 421.786 160.141 359.228 108.477C296.548 56.8012 270.301 173.948 147.388 171.301C62.2399 169.455 -45.3477 49.4305 -157.507 118.01" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.399 75.5286C637.967 76.0456 582.48 29.447 529.611 114.985C476.743 200.522 420.795 161.353 358.144 110.431C295.263 59.4674 268.7 171.902 145.193 169.461C59.7542 167.745 -46.4728 52.6962 -157.155 120.749" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.4 77.0943C637.251 77.8861 580.415 30.1861 527.421 114.366C474.427 198.546 419.803 162.619 357.067 112.406C293.985 62.1013 267.105 169.86 143.004 167.621C57.3202 166.036 -47.5976 55.9619 -156.808 123.487" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.401 78.6657C636.535 79.6998 578.344 30.92 525.251 113.748C472.157 196.575 418.831 163.842 356.009 114.338C292.706 64.7731 265.504 167.814 140.784 165.775C54.8412 164.326 -48.7803 59.227 -156.488 126.225" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.401 80.2316C635.819 81.5458 576.279 31.6592 523.041 113.134C469.803 194.609 417.937 164.991 354.913 116.265C291.539 67.2957 263.903 165.74 138.621 163.909C52.4072 162.59 -49.8472 62.4668 -156.115 128.916" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.402 81.7974C635.104 83.3486 574.214 32.4146 520.851 112.516C467.488 192.617 416.965 166.21 353.829 118.245C290.28 69.9623 262.301 163.715 136.426 162.095C49.947 160.908 -50.9725 65.7595 -155.769 131.703" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.402 83.3631C634.381 85.205 572.143 33.132 518.661 111.897C465.179 190.662 415.987 167.427 352.752 120.225C289.04 72.5967 260.706 161.696 134.238 160.25C47.5065 159.199 -52.0972 69.0198 -155.423 134.441" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.403 84.9235C633.666 87.0293 570.078 33.8657 516.471 111.273C462.864 188.68 415.015 168.645 351.675 122.136C287.724 75.2301 259.086 159.632 132.05 158.41C45.0341 157.489 -53.2221 72.2909 -155.076 137.18" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.403 86.4949C632.95 88.8647 568.006 34.605 514.281 110.66C460.555 186.715 414.036 169.863 350.598 124.106C286.497 77.8704 257.504 157.586 129.855 156.548C42.5745 155.758 -54.3466 75.53 -154.73 139.897" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.404 88.066C632.234 90.6943 565.941 35.3334 512.084 110.046C458.226 184.759 413.045 171.086 349.514 126.059C285.232 80.5045 255.922 155.54 127.666 154.73C40.1208 154.07 -55.4719 78.8172 -154.377 142.657" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.404 89.6319C631.518 92.5241 563.876 36.078 509.894 109.428C455.911 182.778 412.118 172.305 348.437 128.013C283.966 83.1442 254.321 153.499 125.472 152.884C37.6608 152.361 -56.5969 82.0831 -154.031 145.396" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.399 91.1975C630.796 94.3536 561.805 36.817 507.716 108.82C453.628 180.823 411.12 173.538 347.373 129.977C282.708 85.789 252.72 151.463 123.296 151.055C35.2139 150.662 -57.7089 85.3596 -153.672 148.145" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.399 92.7634C630.08 96.1834 559.74 37.5508 505.514 108.191C451.287 178.83 410.129 174.745 346.277 131.92C281.43 88.4177 251.112 149.405 121.063 149.204C32.722 148.941 -58.8723 88.6087 -153.364 150.872" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.4 94.3292C629.364 98.0131 557.669 38.2899 503.323 107.572C448.978 176.854 409.144 175.969 345.199 133.879C280.171 91.0627 249.511 147.369 118.9 147.364C30.2878 147.238 -59.9716 91.8803 -152.972 153.601" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.4 95.9002C628.623 99.8316 555.604 39.0342 501.133 106.959C446.663 174.883 408.166 177.192 344.122 135.827C278.893 93.6965 247.91 145.317 116.705 145.518C27.828 145.523 -61.0964 95.1405 -152.652 156.349" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.401 97.4662C627.958 101.678 553.52 39.7626 498.943 106.34C444.367 172.918 407.181 178.41 343.071 137.781C277.647 96.3311 246.341 143.271 114.543 143.679C25.4006 143.808 -62.1955 98.4068 -152.299 159.088" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.401 99.0319C627.217 103.508 551.467 40.4964 496.753 105.721C442.038 170.946 406.196 179.633 341.961 139.75C276.35 98.9701 244.713 141.24 112.328 141.855C22.9146 142.114 -63.3466 101.688 -151.953 161.843" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.402 100.598C626.494 105.337 549.402 41.2355 494.563 105.103C439.723 168.97 405.211 180.856 340.904 141.688C275.097 101.615 243.132 139.178 110.153 139.993C20.4743 140.389 -64.4519 104.938 -151.587 164.565" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.403 102.142C625.779 107.145 547.331 41.9478 492.367 104.463C437.402 166.977 404.226 182.095 339.808 143.641C273.806 104.254 241.511 137.136 107.913 138.153C17.9503 138.679 -65.6281 108.198 -151.285 167.303" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.403 103.729C625.063 108.997 545.266 42.7084 490.176 103.871C435.086 165.033 403.242 183.307 338.724 145.594C272.528 106.894 239.897 135.089 105.751 136.313C15.5419 136.97 -66.7209 111.464 -150.907 170.042" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.397 105.301C624.347 110.826 543.201 43.4477 487.986 103.252C432.771 163.057 402.25 184.53 337.621 147.548C271.25 109.539 238.29 133.048 103.537 134.467C13.0565 135.26 -67.8714 114.735 -150.586 172.78" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.398 106.866C623.631 112.672 541.129 44.2028 485.796 102.634C430.462 161.064 401.272 185.754 336.57 149.502C269.978 112.178 236.714 131.002 101.342 132.627C10.6028 133.551 -68.9966 117.995 -150.24 175.519" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.398 108.432C622.909 114.486 539.065 44.9204 483.606 102.015C428.147 159.109 400.274 186.982 335.493 151.455C268.7 114.823 235.119 128.955 99.1792 130.771C8.18161 131.842 -70.0829 121.261 -149.868 178.274" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.425 109.998C622.219 116.316 537.019 45.6545 481.461 101.402C425.902 157.15 399.283 188.21 334.409 153.409C267.423 117.451 233.518 126.914 96.9587 128.941C5.7028 130.127 -71.2524 124.521 -149.553 180.99" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.406 111.564C621.484 118.145 534.935 46.3935 479.232 100.783C423.529 155.173 398.298 189.455 333.364 155.363C266.176 120.113 231.949 124.868 94.8279 127.113C3.28115 128.434 -72.3135 127.799 -149.143 183.746" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.387 113.135C620.749 119.975 532.87 47.1273 477.022 100.164C421.175 153.201 397.3 190.667 332.255 157.31C264.86 122.757 230.322 122.821 92.6073 125.278C0.795598 126.729 -73.4705 131.069 -148.829 186.489" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.368 114.7C620.007 121.804 530.76 47.8657 474.813 99.5453C418.866 151.225 396.27 191.895 331.146 159.263C263.549 125.401 228.689 120.773 90.3802 123.448C-1.69652 125.03 -74.6278 134.345 -148.508 189.238" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.401 116.267C619.324 123.634 528.727 48.6054 472.655 98.9272C416.583 149.249 395.311 193.124 330.094 161.217C262.297 128.046 227.152 118.733 88.2245 121.576C-4.12374 123.294 -75.72 137.585 -148.129 191.95" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.402 117.832C618.608 125.464 526.656 49.339 470.458 98.3138C414.261 147.289 394.313 194.358 329.017 163.171C261.012 130.696 225.525 116.686 86.0103 119.736C-6.59681 121.606 -76.8644 140.85 -147.802 194.688" stroke="white" stroke-miterlimit="10"/>
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<g style="mix-blend-mode:overlay" opacity="0.5">
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<g style="mix-blend-mode:overlay" opacity="0.5">
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</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.397 122.535C616.46 130.953 520.455 51.5511 463.888 96.458C407.322 141.365 391.32 198.048 325.799 169.032C257.159 138.646 220.728 110.53 79.4581 114.21C-13.9502 116.456 -80.2196 150.643 -146.743 202.904" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.398 124.101C615.738 132.783 518.39 52.2847 461.698 95.8393C405.006 139.394 390.335 199.293 324.702 170.985C255.874 141.296 219.126 108.505 77.2698 112.37C-16.4102 114.763 -81.3444 153.908 -146.397 205.643" stroke="white" stroke-miterlimit="10"/>
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<g style="mix-blend-mode:overlay" opacity="0.5">
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</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.399 127.232C614.306 136.442 514.253 53.7575 457.305 94.6071C400.356 135.457 388.32 201.77 322.516 174.892C253.298 146.607 215.924 104.417 72.8864 108.685C-21.3234 111.328 -83.5942 160.413 -145.692 211.12" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.399 128.798C613.584 138.277 512.182 54.4967 455.127 93.9888C398.073 133.481 387.322 203.004 321.465 176.846C252.007 149.262 214.329 102.365 70.6918 106.845C-23.7832 109.635 -84.7257 163.705 -145.351 213.853" stroke="white" stroke-miterlimit="10"/>
</g>
<g style="mix-blend-mode:overlay" opacity="0.5">
<path d="M639.4 130.37C612.875 140.107 510.117 55.236 452.937 93.3703C395.758 131.505 386.318 204.243 320.388 178.799C250.716 151.918 212.734 100.324 68.5034 105.005C-26.2429 107.92 -85.844 166.966 -145.005 216.597" stroke="white" stroke-miterlimit="10"/>
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<g style="mix-blend-mode:overlay" opacity="0.5">
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<g style="mix-blend-mode:overlay" opacity="0.5">
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<g style="mix-blend-mode:overlay" opacity="0.5">
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<g style="mix-blend-mode:overlay" opacity="0.5">
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<g style="mix-blend-mode:overlay" opacity="0.5">
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<stop stop-color="#1EDAE6"/>
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</linearGradient>
</defs>
</svg>

As you can see the "wave mask" doesn't fill entire space of container. Have any suggestions?

Wrap with this Container.

Container(
  width: double.maxFinite,
  height: double.maxFinite,
  child: SvgPicture.asset("/path"),